Breastfed baby not gaining weight

So my baby was discharged from the hospital weighing 7.5 last Wednesday and just had his first appointment yesterday and he only gained an ounce in a week. He eats all the time and doesn’t seem like he’s hungry when he’s done. He unlatches when he’s done and seems satisfied so idk why he’s not gaining much weight. We go back next week for another weight check and they want him gaining an ounce a day. Anyone else have this problem? He eats so much I don’t even get engorged unless he’s sleeping 3-4 hours which is only once or twice a day. Is this normal?