How do I find out who I really am?

I just want to be one person all the time, feel comfortable with it, and know deep down that I'm being honest with myself. I am not very sure of myself in general, and people immediately sense it, and as a result, I usually don't get much respect from people. I feel like if I can be one person all the time and know deep down that's who I really am, I would be able to have confidence with people and big decisions in life. I am also extremely ADD so I often bounce around with different identities. I am a senior in College, and while being here, I have toggled between being a frat boy, a wigger, a jock, a health nut, a pothead, and a Christian...but I never managed to stay consistent with any of those identities. I know you can be a little bit of a lot of things, but I just want to know for sure what those are and be CONFIDENT about it. What do people usually go through to find the right answers?