Freaking out and anxiety in a little class of 12 people audiovisual sound class

Well.. I don't know where to start but right now i'm in a delicate position socially. In life, mostly i feel great with people when I'm one to one with somebody but once I have to interact with so many people I feel so scared because of old traumas (got bullied during all the secondary school and the beggining of university). My last two years were the best of my life because I felt relieved, well in my body, I developped so many new passions but it's like I was just born 2 years ago because all the past years got erased from my mind due to hard isolation, from end of middle school til the 3rd year of university (i've done a master's degree in cinema).

Now I've decided to resume my studies in an amazing public school in Paris that was very selective, we are only 12 and most of us, even all of us are excentric people, though I'm feeling kinda overwhelmed by all these emotions and interactions. I'm constantly scared to be out of place, to not be good enough, to be not funny or reactive enough. But the thing that terrifies me the most is the act of be always funny, great, interesting and not boring in the same time.. I've always felt more confident with introvert people because they are better listeners, and the alchemy is way better for me most of the time. But once there is too much ego I'm terrified about these people and I'm overthinking af.
I'm terrified by social pressure, I know that I can talk easy to anybody but sometimes I'm scared to some type of person because they made me think of good confidence and so instantly I feel insecured because they seem overconfident or cold. That's killing me because I'm trying to avoid these people while they could be really nice, but I'm just like I don't want to bother them. I've growned in a constant stress environment with my parents, and for the first time I have my first flat in France. I'm fucking happy about it and in the same time it's like all the pressure was transmitted in my brain and body, I feel heavy and tired about it, and I don't want to endure this year one more time, to be isolated or too feel too dumb or disconnected from the others of the class.

For precision, I'm in apprenticeship so it's like 3 weeks in class and 3 weeks in a company, I have the same problem in company because there is one young guy that has ego af and that's killing me too. Anyway, in life, due to bullying, i've always felt being the spectator and rarely the actor concerning the real life, it's like I always have a delay in my brain and the right timing to say the joke or to say something interesting is delayed. Most of the people in my class seemed to have had a or multiple group of friends where they could feel great and happy, be themselves, dare to say things without being judged. And now I feel like it's too late, I'm 24 and I've missed this teenager and young adult "group of friends era", so I don't have all the social skills and codes of this life, I feel sometimes connected and sometimes so disconnected, and anxious.

My brain is constanly overthinking and everything is overwhelming for me, I'm feeling so tired at the end of the day. In artistic domains, there are so many of "cool kids" that don't care to anything related to that, I want so much to talk about it with others but in the same time I don't know to be this annoying guy talking about his own problems while we just know for 1 week.

I bite my skin very hard every day when I'm anxious, and it makes me lose all concentration on the present moment. I'm also overstimulated by everything that's going on. I've always been a bit of a dreamer in life, and I think I have ADHD. Although I haven't been diagnosed, I have all the characteristics.

In short, overall I am terrified of being rejected by others, of being too annoying or boring, not funny enough, but above all of not deserving my place because it is a very selective promotion and, for example, everyone else plays music while I am a beginner and don't know much about it. I am more focused on everything related to sound in cinema.

What can I do ? Please help me.