Beginning formula

Brittany
I just started to wean my little guy from breastfeeding during the workday. He still gets breastfeed in the morning and at night. He's currently getting 3 bottles a day with about 4 oz breast milk to 2 oz of powdered similac for supplementing. He's doing well taking the bottles, but I've noticed that he poops a lot now. Used to poop once a day max and now poops anywhere from 3 to 7 times. Is this normal during a transition period? I'm worried it's going to get even worse when he's on more formula then 2 oz. He has his 4 month checkup on Wednesday so I can discuss then.