Not gaining enough weight!

M
Just came from the doctors and she said that I'm not gaining "enough" weight than I should for being 26 weeks pregnant. I was 157 pre-pregnancy, and have gained 12 pounds now. Baby is measuring good, at 2 pounds. The doctor even asked whether I was on a diet (which I'm not) but I do notice I don't eat more than I did before pregnancy. I can't seem to eat If I'm not hungry. What do you ladies suggest I could do?