Ahhhhh! freaking out! Help please!?

I'm 17 & 14 weeks pregnant. The doctor said there was a potential for twins. I was really excited to be a mommy, but now I'm kind of scared because I'm so little. I've started to show more within the last week, but again my size is worrying me! I'm only about 5'3 & 117 lbs. Will my size affect the delivery? Please help me!! I don't want to go into the hospital all panicky when it happens.