It can take a while to feel comfortable in an already established group. I suppose, when it was your recovery group, no one had been there much longer than anyone else, so it was more and even footing.
Just don't put yourself under pressure to speak out. It's fine to just go along, listen, get to know the dynamics and personalities a bit. Then, ovr time, I daresay you'll find one or two people you're comfortable with. Then a couple more and so on.
I would say though, if there are opportunities for helping with setting up and clearing up, then grab em. It's often easier to chat while focussing on a shared task.