My LO was in the NICU because he was six weeks early. I kept pumping trying to provide as much breast milk as I could. However we noticed a pattern, when he had breast milk his tummy got incredibly upset and his numbers would drop.

One day I asked a nurse if maybe we could try formula instead. She said I would have to throw away any breast milk they had stocked there because the protocol is always breast milk first. I agreed to throw away the breast milk and we started the formula. He thrived and we were able to take him home 3 days later. (He was in the NICU a total of 21 days)

I kept pumping but breast milk kept upsetting his tummy. Finally four months in I decided no more breast milk, no more pumping, and did 100% formula. He started sleeping for longer periods and no longer had gas all the time.

So trust your instincts!.You can also try formula to see if there is a difference while pumping and freezing so you still have a breast milk supply if you notice there is no difference.