Do you feel full?

My twin 4 month old daughters both have G-tubes. One daughter is full G-tube and NPO. My other daughter. My other daughter is taking about 40% of her daily feeds by day. Ive noticed a difference in their feeding and hunger ques. My NPO baby almost always seems hungry. She's constantly putting her hand to her mouth and when she sees her sister being bottle fed she will throw a fit. I was wondering if maybe she doesn't feel full on her feeds. I can't increase it because she doesn't tolerate her feeds increasing very well. She is on high calorie feeds. I asked her pediatrician yesterday and she said she doesn't know. So I'm asking you guys who are full formula feeds, do you ever feel full on your daily feeds?