What should I do if I am too good at languages?

Background: I am 18 and English is my native language. I'm a self-taught polyglot. I live in the United States and have recently been accepted into a college in Bavaria, Germany. I learned German in under a month and I'm almost completely fluent in it. I have been to Germany a few times and it in no way feels like a foreign country to me. I know all of the culture, customs, history, and geography like the back of my hand from using the internet and watching videos. I have already gotten a few confusions over the past few months where people have asked me if i'm German. I asked my German teacher if I was "good enough" and he said that he can't even tell that English isn't my first language. I've been getting a lot of criticism from Germans where they think that I'm American and I didn't grow up in Germany so I can't be German. Germans have been calling me a poser and things like that. I don't really know what to identify as. If I call myself German, I am told that I'm not. If I call myself American, I am told that I'm not American. I don't really know what to do. Am I German? Am I American? Am I both? Is there a specific way that I should present myself? Is there a specific way that I should talk to Germans and Americans? I am very confused. I have already gotten in an argument with someone over this. I just need some advice.<br><br>TLDR: I am an American living in Germany who can speak German perfectly. I am very confused as to what I should call myself or what I should identify as. Should I present myself as German or American? Should I speak with an American or German accent? I don't really know.