Weight gain

I'm gaining almost a pound a day, 10 lbs in between my 2 week appointment, now 34 weeks at 30 weeks I had only gained 5 lbs my entire pregnancy now I'm at 22. My doctors swears it's just baby & water weight bc of how swollen I've gotten. Is this normal? Anybody else have any experience with this? Should I get a second opinion. I'm a FTM & at this rate I'm going to end up gaining 50 lbs if I make it to full term which I'm not okay with!