Water weight issue

So I am 36+ weeks and I managed to gain only 10 lbs thru week 26 which I thought was great. I was overweight to begin with and trying to be conscious of how much weight I put on. Now, since week 26 I have gained 2-3 lbs a week and I'm not eating anything crazy, I still work full time on my feet (teacher) and go walking. My blood pressure is great, they tested me for preeclampsia and hypertension and gestational diabetes but all those tests were good. My OB said last week that I need to be careful how much weight I keep gaining and I'm just not sure at this point how to stop it other than starving (which I'm not doing). My feet have been swollen for 6+ weeks, I'm sure due to the extra weight. Anyone else having/ had similar issues or just have a thought on what to do?