I pumped and dumped for the first 3 days because of the mag and other drugs, but once I was off those, I was able to pump and store for them to use in the OG and NG tube and I was on a myriad of meds. The did add high calorie formula to the breast milk. My body HATED pumps. I could double pump with the hospital grade machine sent home while looking at a pic of baby girl on her worst day (@ 36 hours she took a really bad turn) to remind me how much she needed my milk and it would take me over an hour to get at 1 ounce feeding. It was brutal, but I never gave up. Finally just after she passed the 3lb mark after the normal weight loss babies experience, I begged the nurses to let me try to let her nurse. I was initially rebuffed, told she could never lastch and then got pissed. The next time I asked I happened to have an Australian nurse who was an huge advocate of Kangaroo care. I loved the irony, btw. She provided a screen and told me to take off my top and bra, then she stripped Taylor down to her diaper, wrapped a warm blanket over us and said she'd be back with the lactation counselor in 10 minutes. By the time they got there Tay was nuzzling and trying to suckle. They were a bit surprised, and made me promise that I would not get upset if it didn't work. We led her mouth to the breast and she latched like a champ!! About 10 minutes or so, she pulled away and drifted off. She was so zonked that when the nurse had to pull the contents from her stomach (NG tube was still in), Tay didn't wake and the nurse was amazed! Baby girl was able to down more than her normal feeding in a 1/6th of a time it took me to double pump a feeding. She was still supplemented with high calorie with random feedings and even after she was home.
I know I didn't really answer your question, but please don't give up on the attempt to breastfeed. I will have to pull out my medical record to see what exact meds I was on, but I will let you know. Interestingly, I was on FOUR different BP meds when I found out I was pregnant with baby girl. Needless to say those were discontinued and pregnancy-safe ones were prescribed. Again, I will dig out my med records.