I feel I have 2 ppl inside me, but no mmry loss or hearing voices. I just shift personalities?

It is probably just bipolar. You said you don't hear voices, so that filters out schizophrenia. I have bipolar and I am pretty much the same way as you describe yourself. Your mood can change almost instantly. Your happy and laughing and joking having a good time, being as giggly as a dental patient on goofy gas, but then you hear or see something you dont like and all of a sudden the happiness goes away and everything becomes all Mr. Hyde, my brain angry, Hulk smash type craziness. Your not alone in the way you feel. Try not to be too negative about yourself. It's not that bad. Just focus on positive thoughts, do something that relaxes you when you start to feel anxious, and everything would be all right. Don't worry about it too much. This is actually a pretty common thing. Stay true to yourself and don't let anyone bother you about the way you feel. Peace out.