I have 15 days old baby girl.....how can I know my breast milk is sufficient to her and can I start formula milk..because she decrease in her weight 400 grams in 15 days of birth

A. hey mommy so in the first two weeks the baby looses weight however will regain this weight very quickly. usuly they loose any where between 8-10%of the birth weight. so make sure you don't worry about that part. also please note that is your baby has atleast 5-6 wet diapers in one day and is gaining weight weekly after the first 15 days she is all fine and is getting adequate feed.