27 WEEKS AND NO WEIGHT GAIN IS THIS NORMAL?!

Lisett
Okay so my pre-pregnancy weight was 180 and I lost 20lbs! Right now I'm 27 weeks pregnant but measuring 2 weeks ahead and have gained 3lbs so far. I'm a little concerned because I see everyone gaining weight and I'm not. So my OBgyn is sending me to get a 30week ultrasound to measure baby and make sure he's growing at the right speed. I'm curious am I like the only one now adding extra lbs! I'm starting to freak out a little! I eat perfectly fine I just don't understand!