NOT gaining weight

Anyone not gaining weight? I started out at around 168 pre pregnancy. I gained a few pounds at the beginning of my pregnancy. Two weeks ago at my 30 week check up I was at 177 which I had been for about two months. Today at my 33 week check up I weighed 173. So I've lost 4 pounds in two weeks. I'm not sick, I just don't feel like eating anything.  My belly is measuring right on target but I have to have an ultrasound next week to see if baby is growing appropriately.