Nervous for theatre productions?

I'm in one of my school's theatre productions and I'm in two skits. One is 5 minutes, the other 12. I had a great audition so now I have pretty good parts in both of them, but I feel like I'm not living up to their expectations. Anyways, sometimes when I get nervous, my whole body shakes and I can't control it. My hands and feet also get really cold, and my stomach kinda turns. I really don't wanna mess up and forget my lines in the midst of my being nervous, so any advice? I've never been in theatre before and my stomach just churns every time I think about it. They're in the same night, in two weeks. Thankss!