Are your parents American citizens, now? If so, then, legally, I believe you’re American. Otherwise, you must be some kind of European, but I have no idea what. You certainly aren’t a Chinese citizen, although you may think like a Han. Though I doubt that’s the way you think, at least, not completely.
Anyway, that’s the bureaucratic side of the issue. On the philosophical side, you are a citizen of the world. Hell. We all are. You are a mix of cultures, but like everyone, your experience is uniquely yours, and that’s who you are, regardless of any label. You may be comfortable in Chinese society and culture, and you may understand it well. Then again, you may not, if you have been kept separate as you have grown up.
I don’t know how much you know of other, Western cultures. You might not feel at home anywhere, really. You can take that as you wish, but I’d hope you take it as a blessing, and not as a curse. You can cross cultures and understand things in a way that few others can. That’s a valuable trait. I hope it makes you happy, too.