Need advice on breastfeeding vs formula.


So I got a job at this preschool so that my 9 week old can stay with me and I can breastfeed him. I cannot pump enough to give them bottles to give him so I have to breastfeed him on a 3 hour schedule. The teachers in the infant room are telling me to pump this weekend so they can have some frozen bottles. ....but when I pump then I don't have enough for his next feeding. And if I pump while he'd nursing I don't have enough in the other boob for when he switches to other side.

So... The teachers have said they would just switch him to formula. Many other reasons including he takes formula two days a week when he is with my grandmother. But also he is VERY gassy and his stomach hurts when he can't poop and he goes up to 4 days without pooping. This has been ever since he was born. I know the formula and breastfeeding is affecting his stomach so I don't know what to do. Should I just switch him to formula?