27 weeks and hardly showing

I'm 27 weeks pregnant and everyone keeps commenting on how I'm so tiny and hardly showing. Before I got pregnant, I was only about 100 lbs and I'm 5'7. My doctor has been happy with my weight gain (125 now) and at my 21 week scan baby was growing perfectly and my doctor hasn't been concerned with my size. I recently just started showing and my stomach has been growing but I see everyone else's belly pics and have friends that are close to my due date and they all show way more. I'm still pretty active and do pilates most days, so I don't know if this affects it. Has anyone else stayed relatively small in their pregnancy?