I struggled a great deal with this when I was in my late teens, and through my 20's
Figuring out who you are is something that is difficult for many people.
It's important to give yourself an honest evaluation about where you are in life and where you want to be.
I found for me, it helped to think about what I am passionate about. What are my views on various issues? What experiences shaped those views? Are they rational or emotional responses to what occurred? Am I moving in a direction I want to go? Or am I going in a direction In feel obligated to go in?
As you question yourself make sure to answer how you are, not how you wish you were. You may be surprised at how you answer some of those questions. But the more you question yourself the more you get to know yourself.
This worked for me and I hope it helps you out a bit as well