I think simply joining a league is a good first victory in and of itself. You don't have to have it all figured out before you sign up (I have this problem too). You can just go, be a good cat, and talk when you can/want to and stay quiet when you don't. Maybe people will start conversions with you. Maybe you can just join in on the group conversations. Maybe you can simply say "hi" when you show up and "bye" when you leave and that'll be good enough