My process when invited to something

I'm happy to be invited and say yes almost immediately.

Two minutes later I regret accepting instead of saying 'no' or 'maybe, let me think about it'. The feeling may go away if the trip or party or event is some time away.

On the same day, or the night before, or at the latest two hours before, I get horrible anxiety and cancel. Every single time.

Did this routine a few hours ago. Invited to dinner and then going out, a girl I'm interested in invited me. Said yes after some convincing (usually need convincing since I know I'll cancel later, and it's nicer to decline than to cancel.). Went home. Massive regrets. The all too familiar feeling of anxiety hit me. And I cancelled. Cowardly sent a text claiming I had a headache. Didn't answer when they called.