No reason to be concerned if your Dr isnt, for me iv only gained 8 pound im 22 weeks and I was always worried because I didn't feel the baby move but my Dr said the reason that I don't really feel baby move is because my placenta is in the front and acts like a cushion
I'm 19+4 and haven't gained any weight. My baby is growing just fine. Only be concerned if your doctor is concerned. My doctor isn't concerned about mine.