Is this normal!?

From my first doctor's appointment at 8 weeks pregnant, I was 258 lbs. Today I had an appointment at 31 weeks& I am 243. At an appointment I had at 22 weeks I was 247. Some days I feel like I'm pigging out for no reason. Other days I can only manage to eat twice a day. Any other ladies losing instead of gaining? Everything is fine with the baby. With my daughter I only gained 28 lbs. I walk everyday so maybe that could be why?