I feel like I have multiple personalities. What to do?

And as if in different situations, one of them dominates me and brings me either moral harm or pride in myself. In different situations, I feel completely different personalities and start behaving differently, which makes me not real. If I relax even a little bit somewhere in society, for example, walking with my friends, and behave like them (loosely), then I will quickly become quiet and show myself not real. How does this bother me? If it didn't bother me, I wouldn't ask for help, because, on the one hand, it helps me to maintain a balance of normal behavior and not go beyond, but, on the other hand, constantly hiding under a "mask", I won't be able to finally show the real "I" and communicate normally. I will add that, in my opinion, all this is due to my fear of society, by the time I was 13 years old, I had revealed a lot: human cruelty, arrogance, arrogance, thirst for revenge and leadership. I can't help but pay attention to all this because of my character as a modest girl. I also grew up in a decent society and thanks to my parents and loved ones, I grew up well-mannered, compassionate and compassionate. I want to find out if it is normal, at my age and in general, to have such a feature (13-14 years), and if not, how to get rid of it?