Playing in concert is an uncommon situation. There is a piano, you don't know well, there are these people watching you, the room, the reverb, stage fright etc. - and you want to play your pieces in the best possible way. It's very unlikely, that in such a situation you will play as good as when sitting at home at your own piano, without any audience.
You will get accustomed to this sort of events, the more you play in front of different audiences. Don't be that over critical, if something went wrong. That's completely normal. Take it as an important experience - learn from it.