Why do I feel like theres so many personalities in my head and their all fighting to be 1st place

I feel like I change so much at any given moment. Theres so much I wanna change about myself. I feel like I can’t run away from any of my past friendships without looking back and hating myself for things I did and how I acted. I regret everything I do later because it feels like something I’d never even do in the first place. How can my thoughts and feelings about things change so drastically and quickly. I don’t even think I’m capable of anything good. I’ve done such stupid and honestly weird things and I hate myself for it every day. I don’t wanna be me I don’t even know who that is. I want to be consistent about something I want to stop all the mood swings and lashing out. Sometimes things feel okay and stuff but right now, the “me” right now just wants everything else to shut up even though I know this feeling will pass too and I’m gonna feel and think things I wouldn’t agree with right now, I think?? I dont know. I’m so conflicted. I dont ever feel like the same person