Am I being delusional for wishing this or is it actually possible?

While I don’t know if any studies have been done on this, I see no reason why not. If you were to stop speaking your native language and exclusively used English, after a decade or 2 you probably would feel more natural in English than your native. The question is why do you want this? I do think learning another language is very important, but I don’t see a reason to try and replace your native unless if you lived somewhere you can’t easy speak it with others.

>is it possible to become more fluent in it than in my native language? I'm not a professional, but I've learned three languages and I can't imagine becoming *more* fluent in a second language than your first - especially if you start that language at 18. If it is possible it would likely require you to stop speaking your native language entirely, move to an English speaking country, and give it 5-15+ years of heavy study and use. MAYBE by the time you turn 40 you could be "fluent" but I imagine you'll still be **less** fluent than your native language. I know people here in the US who've been here 20 years and they are not at all fluent. But they've had to attend to other matters (besides English proficiency) and they've been speaking their native langue often with their spouse, friends, and family.

Language is almost like any other active skills you can acquire at any given time of your life. The requirement changes as you get older but "impossible" is never going to be the answer.

You’re still young. If you live in English you’ll soon start dreaming in English and that’s when you know you’re there.

There's no reason you can't be fully fluent and even lose any hint of an accent eventually, but your mother tongue will always be hard-wired to some extent. The basic test as to what language your brain is defaulting to is what language you instinctively chose when counting to yourself (without thinking about it at all). You'll probably always still dream in your native language too. But you're well on your way at the point where you're fully thinking in the language and not translating.

It depends on how well you can learn the phonemes. What's your mother tongue? You might have already learnt them, which makes speaking English fluently a lot easier.

Judging from this post alone, you’re doing a fine job expressing your thoughts in English, and you just started a year ago! That’s amazing! Keep going and maybe you’ll get there!

It’s definitely possible—it happened to my grandmother who moved to the US as a late teenager, but she later regretted not being able to freely express herself with her family members abroad.

In my experience, at least in academia, this isn't that rare. A lot of people study English during secondary education, move to an English-speaking country for college, then pursue advanced degrees in English. If they're studying liberal arts, they wind up writing more in English than many native speakers ever *read*, and they're getting constant feedback on their expressive and presentational skills, held to the same standard as native speakers. All the while, they use their native language only to call home / when they visit family. (Except for those students who have friend groups from their home country, anyway.) A lot of such students / professors still have obvious accents, but some don't. Some also, naturally, have gaps in their vocabulary for things like "potty", "cooties", "slingshot" - things that, if you didn't encounter as children, you're only going to learn through reading / watching enough fiction, which not everyone does. But if fluency means being able to comfortably participate in any daily conversation, consume content for natives, and above all, expressing one's thoughts articulately, many of them report being more comfortable in English. Their native language skills are still effectively at a middle or high schooler's level; their English is polished, professional, practiced and eloquent. Both are fluent, but the latter is more so, and the ones who care to aim for it manage even to eliminate the usual caveats of, say, not knowing colloquial expressions or cultural references.

In part, it depends on your definition of fluent. Since you are past puberty, you will probably always have a foreign accent in speaking English. Some languages have a very small vocabulary compared to English. But you can study English vocabulary and improve immensely.

I know a guy named Dorin. He was born and raised in California, moved to Italy when he was 18 or 19, I think. He has been a music teacher (and quite an accomplished cornetto player) in Italy for 40+ years. I saw a YouTube video of him speaking in English a few years ago. It is no longer the language he thinks in. His english was hesitant, and halting. Not terribly so, but enough to tell that he no longer operates in english, but Italian. It was amusing reading comments from his students complimenting him on his italian and that they could hardly hear any accent when he spoke. I remember him as a young man: loquacious in english, and omg, he was such a good musician that the other musicians used to jokingly mutter things like, "We should kill him now before he takes all of our jobs!"

It may depend on the topic. When I was in graduate school, I had a friend who had done all their schooling up to age ~18 in their native language, and after that studied in English-speaking places. They once described the challenge of describing their very technically complex work to their family—not only was there a technical gap, but because they had studied these topics in English, they had never learned how to explain the ideas in their native language. If you go into a field you don’t know much about right now, you may find that you know a lot of English words for things you never learned in your native language.

“Possible” yes, definitely, as a lifelong project. With deliberate, concentrated study of any language you can become more knowledgeable about it than any native who is less well schooled. Some people who have changed nationalities never lose their foreign accent, although their fluency is first-rate. Others will be hard to distinguish from natives. I don’t know what makes the two so different. Bilingual folk sometimes speak about their languages “blending,” and also about losing the language they were born into after many years of disuse. If you love English, keep pursuing it seriously and I expect that you will take it as far as you want or need to. I’m sure your native tongue has its charms, too. No need to regard it as inferior in any way…

Doesn’t seem like you’re asking if you can pass a test. Everyone learns at their own pace, regardless of age. There are migrants in many countries who’ve lived there for years and never learn the local language. Maybe, and just maybe, you’re asking if it’s possible to live and think in another language so deeply that it becomes yours? If so, then yes, it is. And many people have done it. It depends on how much conviction you have to make it yours, how much noise you can tune out, and how willing you are to stay uncomfortable until you’re not. You might always carry your native tongue, but that’s not a weakness. It’s a foundation. You came from somewhere, and you belong there. That doesn’t mean you can’t belong anywhere else. Seeds germinate wherever there’s fertile ground. Also, fluency isn’t about how fast you speak. It’s how you feel in the language. Take Luka Doncic, the NBA player. He’s fluent, but he’s not changing how he speaks English to sound a certain way for the media. He’s just being himself. And maybe when his shooting from the logo, maybe he is thinking in his native tongue. Who knows. Regardless, that kind of fluency comes from immersion, repetition, and real connection. Not age. If this language feels like home, keep walking toward it. You’re not behind. The fact that you’re brave enough to put this out there, and question yourself, already signals that you’re on the path. The right path. Wisdom in motion.

no. prepositions are impossible to 100% master outside your native language. prepositions on their own are so ambiguous that they just take native-level muscle memory. i have a friend who’s a native german speaker but has been learning english for several years and still slips up and says they went someplace with their car or with the bus instead of in their car or on the bus. tl;dr prepositions need native muscle memory and are likely impossible to get perfect