Continue with the therapy. Continue on. I know that answer doesn't sound fun, but it's true.
It will be the accumulation of therapy, continued reinforcement that adds up, that allows you to tell yourself that maybe you do have things to say. Maybe you can talk with people. You're talking with me right now, by writing what you did. Of course you have the ability to talk, of course you can make small talk. You already prove that you can do so with your housemates, and with the people at your church. YOU DID DO IT!
We just don't need to judge how we did on that. That's not useful or rational. Everyone here will understand how you feel.
You do not need practice on how to speak or make small talk. You need the continued therapy and cognitive ideas to allow you to be rational about this action, before, during and after. And then with time and actually doing it, yes, you'll feel more confident that you can do it just fine, just like everyone else, and just like you do now, except with a rational foundation from which you don't go into the over-thinking about it.