Weight gain 😳

So I've been pretty good eating Healthy and staying active and only putting on about 15 lbs the first 32 weeks of pregnancy. I was 135 pre pregnancy 5'2". All of the sudden I'm gaining it like crazy with no change to my diet or routine. I'm so confused. I put 6 lbs on in 2 weeks at my appointment last week and my dr is not happy. I've been eating healthy all week and drinking lots of water and still put on an additional 2 pounds this week! I dunno what to do.. Is it water weight? Like I feel like I'm gonna have to starve myself in order to not put on weight. Anyone else having this problem?