I feel like I have no personality. What do I do?

Ok, I am a teenager, and it might be just the hormones, but to me it feels like I'm not even sure who I am anymore. Basically, I see something interesting and decide, oh I should be like that. For example, I'm a vegetarian. Sure, I believe that eating meat is wrong, but also I think it's cool to be something other people are not. But, behind all these fake things that I use to make myself up, I really don't know who I am as a person. Am I nice? Mean? Rude? Fun? Happy? Quirky? I'm not sure. I truly have no idea who I should be or what I want to do with my life? I'm not sure I even know what I like to do in my spare time. I used to love to draw, but that was because some of my friends were going through an arty phase. I like to write, but that is because right now, a lot of my friends consider themselves writers. I'd really like to stop becoming what my friends, or even just people around me expect me to be. I would really like to be me... whoever that is. If you answer this, thanks! I really appreciate it. :]