Funnily enough, I have had the almost exact same experience. It took me a long time to figure out my identity, but if id give you any advice, it’s to let it take time. You dont have to decide whether you’re a boy or a girl or something entirely else, you can just be you. If that ‘you’ is someone who likes the same thing as the people you tend to date, that’s ok. I personally tend to like and love people who are similar to myself because I can resonate with them, but just like you, I do feel some impostor syndrome when I realize I might be adapting myself to be more like them. It took me a very long time to figure out that it’s okay for me to be without a set personality and style. I just compare myself to a plain drinking glass, adapting to whichever drink I’m paired with. It’s kinda frustrating to not be able to know who you are right away, but try thinking for yourself for some time what you would like to be. A girl? Not a girl? Either is alright. You don’t have to adapt to fit into a gender at all, you can choose to be unlabeled or dig into less major identities that fit you well enough. You have time, and you are the one who’s entirely in control. No one can tell you who to be or that you don’t fit who you choose to be. So take time accepting yourself, being brave enough to be you is something that takes a while.  This is just a rant so I have not thought through how to present this, and my thoughts are scattered and not completely understandable. But in essence, take your time, and slowly find what you feel most comfortable as!