I think a lot of people over react with there reaction.... I get omg your so tiny and the next day someone says I'm huge lol don't worry about it
As long as your uterus is expanding, you're good. Your doc measures it at every appt. Some women are just lucky and stay small
Don't worry about size. At 39 weeks I was beyond small and she came out perfectly healthy and sized. Even then I could still hide that I was pregnant and I looked like I was 3-4 months along. I'm also only 5' 2
Don't worry, you'll pop out more. I popped out around week 25 or so but everyone is different. Make sure you keep gaining wait and feel her kicking and you are good.