Help breastfeeding dilemma

I had my Lo via csection 5 days ago, she was flat upon arrival and had swallowed a considerable amoubt of amniotic fluid. She was transferred to neonatal unit where she was given antibiotics and fluid. Which mesnt skin to skin was delayed for 12 hours, then which she was allowed to visit me on the ward but only for short periods of time. The public health nurse visited me day 4, me and baby given clear discharge to go after day 3. When the public health nurse visited my baby has lost 10% of her original weight from 4.12kg to 3.7 and insisted I top up with formula incase the baby lost more weight. I thought this amount seemed like a normal weightloss and now my husband is so worried he's insisted we change to formula. My milk hasn't fully come in yet and have Been so upset. Obviously I want to make sure my baby is healthy so if that means formula then so be it. But I feel like mabue she's being a tad quick to insist formula as she's only 4 days old