weight during pregnancy

🤱🏻mon • Baby Finn Born 10/6/17💙
So my pre-pregnancy weight was 101 pounds ( I'm 5'2"). I dropped down to 92 pounds in the first trimester due to severe morning sickness. Around 16 weeks, I gained the weight back up to 102 pounds. I am now 20 weeks and I've weighed 100.4 pounds for the past two weeks... My belly looks like I'm 12 weeks pregnant, I had an ultrasound yesterday and found out the baby was a boy & doing well. Everyone keeps asking me if I'm eating & oh boy am I. I've been packing down an extra 2 meals than usual. Is it okay that I haven't gained any weight or belly by 20 weeks? (I had a flat stomach pre-pregnancy.) I have my 21 week checkup on Friday, but my family is getting concerned that I'm not gaining any weight or belly by 20 weeks.. is this relatively normal?