How do you overcome being nervous in public performing? This comes from feeling inadequate and like you're fixing to make a fool out of yourself in public. Nobody wants to mess up in front of a lot of strangers. Many teachers and performers have proposed lots of ideas and written lots of articles, all trying to help. Most aspiring musicians feel that by practicing and practicing they'll eventually get good enough to be ready and relaxed on stage. While being prepared and skilled enough to have a reasonable expectation of a good performance is important, in my experience with thousands of students it doesn't really solve the inner issue - most students never really feel good ENOUGH if this external avenue is all they pursue. Some teachers focus on learning to relax and focus, clear the mind, positive self-image and belief in their personal worth or ability, and I'm sure if we each took a trip to heaven and God gave us a big hug and told us He loved and believed in us that we'd be able to relax and go for it, but that's probably not something we can count on happening. While these internal approaches may help, their effects take years, even decades to bear fruit.
Each week try taking a different aspect of music (dynamics, articulation, breath control, phrasing, rhythmic accuracy) and focus on it.