Haven’t gained any weight- 20 weeks

I’m currently 20 weeks with our first baby girl and so far I haven’t gain any weight. In fact I have lost 2 pounds since getting pregnant. I had our 20 weeks appoint yesterday and talked to my doctor about this and she wasn’t too concerned. Baby measured perfectly on the ultrasound. I’m just a little worried that I should have gained something already. My BMI is high according to the scale as I am 5’7” and weigh 198lbs.

Has anyone else experienced this??