I ate when I was hungry, and like you, also kept my fluids up, that's really important. I had problems eating at night too, so ate when I could during the day. Maybe also try to vary your diet so that you're eating more fruits and vegies, if you can stomach them. Even nuts and dried fruit can be a good snack (and they can help with any constipation, as well!) Are you exercising? Our dog needs walking twice a day so I have kept that up and I think it's helped to keep the weight fairly reasonable. We don't go far, only 15 minutes morning and again at night but it seems to work well.

I wouldn't worry too much, I lived off potato chips, especially salt and vinegar, for about 2 weeks because that's the only thing I really wanted! There are diets you can follow for when you're pregnant (by that I mean proper balanced ones, not like the cabbage soup diet or anything!!), perhaps talk to your hospital as they'll have dietitians there, and might be able to recommend someone to give you a better idea than my ramblings here!