How much BM are you putting in each bottle?

Hello! I exclusive pump! My little one is about 3 months old! The caregiver is telling me that I should be putting more BM in each bottle. We currently do 4 oz and feed him about every 2 hours. I feel like he spits up even after the 4 but she says that he still seems hungry. He still gets about 33 oz a day. Any advice would be greatly appreciated! I can only find online stuff about formula!