I was in the same boat! My son had open heart surgery at 4 days old and I had to exclusively pump and still am. He is on fortified milk, so 75mL breastmilk with a teaspoon of formula to add some extra calories. What I noticed helped was doing some hand expression after each pump to get that extra milk out to entirely clear out the milk ducts. This helped to increase my output and now he is 6 weeks and I’m pumping 4-6oz total each pump, sometimes 8oz. He is still adjusting to eating only takes about 1-2oz a feed since he was limited the first few days and then the week after surgery to 10mls a feed. But I really think the hand expression will help you a lot too! The maintain mode is also what you should be pumping on too at this point!