same here. my gynae advised to eat as much as possible. drink more milk and eat more red meat to help baby grow. usually i get full very fast so she advised to eat every 2 - 3 hours in small portions and drink whenever i can.
try your best to eat whenever possible. My usual drink is coconut water, date milk (farm fresh kurma milk) and soy milk. my food is beef, oats and lots of fruits.