The answer to your problem
I think I know where you are coming from? When I was younger I had a similar problem. It is all about your mind. Have confidence in your shots and your game. You know that they are good and will not fail you. You must believe in your ability to play well during matches. Also, don't be too tentative. You can't be aggressive if you are tentative. Don't worry about missing shots or getting passed. Just focus on playing the point and winning. When you worry about missing shots, your shots become weak and actually you miss more often, so don't worry about your shots and just play. Focus on one point at a time and believe in yourself and you will play fine.