Could I have a personality disorder?

I'm scared to tell my family and friends whats wrong with me because I don't want them to think i'm crazy. I already have mild OCD and problems with anxiety and my therapist and parents sometimes feel I may be a narcissist but i'm not always like that and it confuses me. What i'm trying to say is that sometimes I feel as if i'm 2 completely opposite people and not just by my moods or how i'm feeling, but my beliefs and everything will switch back and forth. And it's not something i can control it is something that just randomly overcomes me. For example, one moment i will feel like everyone should be created equal, and you should be nice to everyone and act very genuine. but then out of no where, i can become very cruel and mean and to an extreme extent believe that it is okay to kill people and have no sympathy for anyone. I don't understand why I can hardly ever stay in the middle, i'm always switching both roles and when i do i can never understand why i ever felt the way i do on the other side. Is this normal or can this be any form of a personality disorder?