J.C.
Same thing happened with me for both of my pregnancies. With my son I did everything perfectly, and people were telling me I wasn't gaining enough and didn't trust my midwife b/c I wasn't gaining a lot. Then in the last month I gained about 20 lbs. With my daughter I was sick for the last 2 weeks, but still gained 10 lbs or so then. If you're doing everything right, don't worry about it. It may be mostly water and you won't even know that until after the baby is born. If not, it just means you might have to work a little more to lose it if you want.