Char, this whole experience must feel a little bit like a totally new ball game - as Pac says, vag birth, straight to breast, completely different to little DD. I know how stressful it can be worrying about how much he is getting but you need to trust your body will eventually catch up and produce exactly how much he needs. You can make sure he is getting enough milk without measuring how much goes in though - by what's coming out. If he's pooing and weeing lots then he's getting lots of nice milk How many wet/dirty nappies in 24 hours? You'd expect 5-6 heavy, wet disposables in 24 hours. Maybe even more at this age

Also - if you are worried about how much milk you're making and he's getting, best solution is to put him on the breast more often. If he cries, stick him on. Looks hungry, stick him on. Wants to sleep, stick him on. He should be feeding anywhere from 8-12 times in 24 hours, more is ok too!

Has he been weighed recently?

I'd also second the propping the mattress up idea. We used a roll up towel underneath the cradle mattress to keep DD elevated. That might help!