Oof, it sucks that it's such a small group. Larger cohorts usually mean more formed groups, so if you don't mesh with one you could mesh with another.

There's always gonna be some sort of "in" group, but I think it's important to view what makes them "in." Is it because they are cruel and mean girl-y (I hate that this is gendered, but so is the word "catty" and others don't have the right connotation), or because they're outgoing and accommodating?

If it's the latter, and you're having anxiety, it can also be good to talk to a group member you trust more about it. If it's the former, then treat it more like a workplace relationship. (I'm a huge fan of AskAManager, and she has a bunch of ways/tips to act more coolly toward coworkers if you have no interest in engaging).

Also, don't be afraid to reach out to old friends, family, or even a therapist.