Great book for you to read - Child of Mine by Ellyn Satter. You can get it on Amazon. It really helped me feed my second child (also with cf) well. The book goes through what a baby should be eating and what age. It also addresses special needs babies. The only thing you can do is offer high calorie foods when your child is hungry. Children and babies will only eat what and how much of what they want. You will always hear "how many" calories you cf baby will need. But as my children's pediatrician says, babies don't read how much they need to eat. I had tons of feeding problems with my daughter starting at a month of age. My best advice is to try not to get too worked up about how much your baby is eating. I know it is hard when their weight is a concern. The dietitians often don't know this, but how many much your baby eats is out of your control. Babies do best when they get to decide how much they eat. The more you force, the less they eat. I learned the hard way. My daughter is 8 and I still have to pick up the fork to feed her. Let your baby try and feed themselves soon. I have a baby who is 6.5 months old. He is sitting at a highchair a few times a day putting cheerios in his mouth. He is also feeding himself bananas and shaved turkey meat. He is starting to want my older kids foods (pasta, yogart, etc). So he is now eating that at meal times too. I wanted to control my daughter (first born with cf) so much as a baby that I just kept feeding her baby food because I was in control. Big mistake. With my son, he screamed when I would open a jar of baby food about 9 months old. Good thing, because it was so much easier for him and me if he would eat regular food. He also learned to enjoy eating. Just try and enjoy feeding times. Weight gain for our kids is a life long struggle. I would just focus on getting your baby to enjoy eating so it is less of a struggle later on.
Sharon, mom of Sophia, 8 and Jack, 5 both with cf, Grant, 6 months no cf