As soon as you ask yourself "Am I playing good enough?" it's over.
You'll never play well if you're asking yourself this question.
Instead, think of yourself as a train conductor. Your job is simply to stay on the track. It's not to drive the train "better" or with more flair or with a sense of style. It's simply to stay on the track.
How does this translate to the piano? it means to simply listen to the music and focus on what's coming up next. Don't worry about what the audience thinks, whether you played better yesterday, or what your piano teacher is going to say after your performance.
Simply stay on the track, and enjoy the ride.
As long as you do this, you'll be fine.
Get my free ebook: Left Hand Techniques for Jazz Piano
You'll also get my weekly jazz newsletter with practice tips and inspiration