You're never going to have a perfect game. Sure you might play well, but it will never be perfect. You'll never make 100% of shots, you'll never get 100% pass completion, you'll never get a perfect dig 100% of the time. The point is, you'll nevr be 100%. That said, it doesn't mean you shouldn't give 100%. You should always try your hardest. If you're not trying your hardest, you're still your own worst enemy.
When you accept that you're not going to be perfect, then you can forget all of the mistakes you make and just try your best. Just because you're not a perfect player doesn't mean you aren't succesful. Success is helping your team with your strongest attribute in the game. Whether it be shooting, defense, running back, digging, hitting, goalkeeping, or anything else, if you've done your best for that game, you've succeeded. Just know that whenever you try your best and forget about your mistakes you can play to your full potential and gain self-confidence.
Love,
MaShayla :)
Here is an article about how to gain self-confidence and making sure you're not hurting someone you mean to be encouraging: https://www.competitivedge.com/self-confidence