I'm 14 weeks and have lost 7lbs...was actually scolded by my dr on wednesday because of it. She almost went as far as accusing me of not eating. I have been on zofran for severe morning sickness so I can eat. I have 3 other children though, I swear chasing my 1yo son and keeping up with a 4 bedroom house is why but I'm not sure. Just keep eating, you will eventually start gaining weight at some point.
I'm 29 weeks and I've lost almost 50!!! Baby growing safe and healthy doctor isn't worried.
I am 16 weeks pregnant and have not gained a pound. With my first baby I lost 9 lbs by 20 weeks. Every body is different and it's okay. You'll gain it eventually and be grateful you have good genes!