Breastfeeding but baby not gaining weight quickly

I’m wondering why the heck my little guy isn’t gaining a lot of weight quickly. He was born 8lbs 5oz and just hit 8 pounds today at his two week appointment... he ended up losing more than a pound after birth (it took forever for my milk to come in after csection)

I feel like I have enough milk but it just doesn’t fill him up :/ I’ve had to start supplementing a little after feeds cause he’s still hungry.

When I pump I get 2oz on each side which I’m not sure if that’s bad or not but I don’t know what to do to make my milk more filling 😩