That's normal. If you move to Poland from wherever, don't expect you'll ever become Polish. Not really. Even if you are slavic as f. You have a better chance if you speak flawless Polish with flawless neutral polish accent (and look slavic as f). But as long as people know you came from other country and didn't have any polish ancestors you'd still be foreigner. But we will respect you for doing well to blend in.

Only America is a country where you can call yourself American after living there for few years.