Hello. After birth, the baby only poops once, i.e., on the second day,…

Hello. After birth, the baby only poops once, i.e., on the second day, after we get discharged home, and my little one also doesn't poop. I called the pediatrician, who said that the child is not being fed enough. After we did a Microlax enema, everything is fine. Started giving formula milk of 30 ml three times a day in addition to breastfeeding. I thought everything was okay, but the little girl again doesn't poop. What should I do? Can you please advise?