Honestly I'm not sure if I've ever known who I am but more and more recently  (since I've been at university) I can't stop stressing myself out over not knowing who I am. I meet people, I try and be what they expect me to be or copy them, and then when they leave I completely have to reinvent myself to forget that that bond ever happened. This has happened with what seems every relationship/friendship I've ever had, some more obviously than others. I don't know what I want to do because I don't know who I want to be and whether I can 'maintain' that persona for long enough.. 
Sorry if this is all jumbled I just needed to get this out. Does anyone else here feel similarly?