11 weeks and has started latching now

Tota • Vet 🥼 ! LA girl ! 👧🏻 1st time pregnant 🤰! EDD June ! Dog Mommy 🐶🐶 🐶

My baby has finally stated latching. I use to pump and supplement with formula. I have stopped pumping as he latches. How do I know he is full n I don’t have to use formula anymore?