All babies are different and if he's genuinely hungry, I'd say let him have as much as he needs. At 9 months, my daughter went from having 5 to 4 bottles a day (she dropped the night feed) and by 10-11 months it was down to 3. She was fed on demand and I made no conscious effort to encourage her to drop bottles it just happened. Most babies really pick up the amount of solids they eat around 9-10 months, so I'd say expect to see that happen soon and when it does, he'll likely want less milk. If he's eating solids well, then he knows what he's doing. I'd just go with the flow and wait for him to let you know what he needs. It doesn't sound like too much to me. He's still little and I think you'll see a lot will change in the next couple months.