how to go from antisocial to friendly in the same social space naturally?

i'm 17 and have been in this youth theater group for years and i really want to become closer with my cast mates. i used to struggle with severe social anxiety + i'm just naturally very introverted, so i would isolate myself from the group and come off as very serious in everything i did, even though i'm not really like that at all. i'd say i'm very unserious, and when i'm with my boyfriend and people i'm close with i become so energetic and goofy for lack of a better term 😭. honestly i become almost insufferable with brainrot humor and all.

i really want to have some of that same energy at my theater and there's this one friend group i want to be part of there. i think they want to be my friend too or at least some people do, but i just can't bring myself to act the way i want to. i feel like if i just started acting like myself it would be such a drastic switch from the super stoic and quiet person they've grown accustomed to. advice?