FTM worried..

I'm almost 17 weeks and I just worry that I'm not showing at all. Some days I think I am, and others I don't have a belly at all. I've been so sick that I've only gained 5 pounds so far, but I just worry that she isn't growing. Many women are surprised I'm pregnant because I don't look like it at all. I always see other pregnant women who are my same weeks or even less and showing way more! My doc says its normal not to show early since I'm rather small to begin with...I just constantly worry