Try to eat small meals and then add fruit or veggies as snacks. That way baby can be getting everything it needs. And drink a lot of water. Try to cut down on oil and junk food (if you do eat it) it should help.
Maybe it is not the amount you eat, but what you eat? I do eat a lot, but mainly fruits and vegetables (i'm addicted to raw veggies atm...). Maybe experiment a bit with leaving out some things from your diet? I can't eat to greasy food for example. Garlic and onions are problematic too etc