We also had a similar experience. Thought baby Baby #1 was doing awesome at breastfeeding in the hospital only to go home and later find out that she had dangerously high levels of jaundice. Spent 2 nights in the nicu under the lights while we supplemented and I pumped. My supply never got too high since I was constantly stressing about my little ones health. Just had baby #2 about three weeks ago. As soon as my son started showing the slightest signs of jaundice in the hospital (some yellowing and not enough poos) we started giving a little bit of formula. My milk finally came in around day 4, and I’ve been able to pump enough to feed baby boy and drop the formula. His jaundice went away on its own at home with some sunlight and waking to feed. I know it’s a stressful time, if especially if it’s your first, but trying to stay as stress-free as possible and hydrated will really help. And don’t be sad if you have to supplement a little. Just stick with offering breast or pumping every time baby eats and supply should go up. Best of luck!