How much does your 3 mo old eat?

My dude takes about 4 oz every 3- 3.5 hours. Recently his weight gain has stalled so I’m trying to up him to 5 oz, but he doesn’t often finish. I also sized up the bottle nipple, previously using size 0 tommee tippie and now using size 1, in hopes that he will take more per feed.

I’m an under-producer and have only been giving 1 formula feed per day. Recently though he’s decided to nurse first thing in the morning, and actually seems satisfied and refuses a bottle top off after. I still pump 2-3 oz after he nurses though, which is my usual amount per session through the day.

LSomething doesn’t seem to add up. I’m thinking this might be why the sudden stalled weight gain. How much per feed does your similar aged baby take?