Fomular and Breast milk????

T

My baby girl is 3 months old now

She’s breastfed through out the day, she feeds for 20-40 minutes then falls asleep.

I pump for the night but because I feed her at 11pm ( her last feed before she goes to sleep) there is little milk left so I can only get 4oz ish for the night.

Can I just give her formular in the night and breastfeed her through the day???

Does anyone else do that?

Or Will it make her sicky or is it totally fine ?