normal. say to yourself, i can do this- because you have been practicing and you really can do it. remember how you felt after learning something like how to swim or bike or fill in the blank? it is a great feeling. after performing, there is a similar feeling, joy and sense of accomplishment.
all you really need to think about is playing what you're playing and being focused on it.
it's really fun and you don't have to worry about it. the music sounds really pretty and you just have to focus on your part. other people are nervous too and it's fine to be nervous.
every year the concert is more 