If there is no problem and enough milk supply then why formula milk, go only for breast milk

Breastfeeding has enough antibodies to provide immunity to protect against illnesses. Prebiotics present in BM also help strengthen the immunity. You can discuss with paediatrician for one closest to BM and feed that

For a new born baby, breastmilk is gold. Please try to express as much possible or feed the baby directly. The prebiotics in breastmilk helps the most in fighting against infections and builds immunity. However, if she needs to choose a formula, choose the one that contains prebiotics. Discuss with the doctor about the same.

Consult lactation specialist