I've been there too, and I think it's pretty normal.

That said, you should probably suck it up and let her go.

For one thing, parents LOVE seeing their kids doing that sort of thing, and for another, it's the only way you're going to get through that nervousness.

In the end, it's more important that your mom has proud memories of seeing her son play than it is if you're comfortable or not at this show.