Help! Tons of Iron = Constipated angry baby

My baby girl just got discharged from the NICU about a week ago on iron added premie formula AND vitamin drops with added iron. She rarely poops (like maybe once every 24-36 hours). It was not quite this infrequent in the NICU and she definitely wasn't screaming bloody murder through a good chunk of it. She's just so miserable and I feel like a total failure as a mom.

We're trying some gas drops which seems to help for an hour or two with the fussiness, but she still isn't increasing bowel movement. I've left voicemails for the nurse at her pediatrician's office but they're terrible about returning calls with any timeliness.

I'm hoping someone might have some non-medication ideas to offer her some relief in the meantime. Suggestions and thoughts are much appreciated!