You'll need to see a pdoc (psychiatrist) to be diagnosed. Self injury and mood swings can certainly happen in bipolar. We have good basic descriptions of the various dfiseases and disorders on PsychCentral; here's the one to Bipolar Disease: http://psychcentral.com/disorders/sx20.htm

Check it out and see what you think. Please, please seek help ASAP. You're too good a person to be hurting yourself. Hang in there; you have a lot of great people here who will help you. I know, I was in your shoes just a few months ago, and these folks saved me me, for real.

BE safe...PM me if you want to.
DJ