Every 2 hours 2 months, could poop be a problem?

I feed my son on demand. He's 2 months and spends a lot of time trying to poop. His poop comes out well whenever he's able to go. Usually it's a lot or a blowout.

After feeding him 4oz within several minutes he pooped. Within 48 mins, as usual he was famished. He ate another 4oz. 8oz total. He did something I have been hoping for since he turned 2 months... Sleep a 5 hour stretch!

I'm speculating that poop keeps him from even eating more then 3-4oz. He always content with less. And doesn't eat anywhere near the 6oz he's supposed to be at.

Any thoughts on this? Advice?

Update! And we were back to our usual program.. a bit worse actually. Btw he's formula fed... I breast feed (latching issues still at 9 weeks pp) and pump, but he gets formula too.