Weight Gain

I'm closing in on 28wks and have only gained about 7-8lbs from my pre-pregnancy weight. I did lose a little in the beginning, but only seem to be putting on ounces every week. Baby A is on track as of last week at a little over 2lbs and baby B is slightly behind at 1lb15oz. My MFM keeps telling me to put on pounds and tell him I'm trying. Ice started to add some ensure to my diet, but other than that, I eat pretty healthy, try to get a good amount of protein. Anybody else having this issue? Suggestions for putting on some pounds??