Since my milk supply is down cause of my mastis I have in my left side it's hard to keep up with my…

Since my milk supply is down cause of my mastis I have in my left side it's hard to keep up with my sons feedings. I used to pump close to 10 oz a session all together now I can barely do 4 oz a session all together. He eats about a good 5 oz every couple hours or whenever he wakes up. So I had no choice but to give him some formula to make sure he has a full tummy. I still pump and breastfeed him whenever I have enough pumped. Or I try and nurse him but now that I have this infection in my left side it takes him longer to get full. So he's been cranky cause he's still hungry so I give him formula to fill him up. I still pump every couple hours and drink tons of water trying to protect my supply, until the infection is gone. The formula is only temporary until I get my supply back. It's a good sign he's eating both formula and breast milk just fine. Has any other moms gone through this? It's tough seeing my son eat formula knowing I can give him the right amount of breast milk to fill him up right now.