My son did the same thing he’d eat spit up, then have the hiccups after before being hungry again within the hour he had acid reflux, I recommend taking him to his doctor
I think this is actually very normal. Newborns don’t know when to stop breastfeeding. So anything they can’t keep down, they’ll bring back up. Both my children were like this at the start of breastfeeding. If it becomes severe with projectile vomiting after every feed then I would take him to get checked.
I think he probably eats a lot. Although usually children eat as much as they need. Try always after feeding to put the baby in a column, Hold upright until you burp, air
He deffo eats a lot he’s gone from 8lbs to 9lbs 3 in 3 weeks
Could be oversupply or could be reflux. I wouldn't pump without making sure oversupply isn't the issue. If you're worried it's supply, try nursing him against gravity (biological nursing position/laid back nursing) if you're able. Might help him not be as overwhelmed. Could possibly help, and a lactation consultant could probably assess you more to confirm if this is the issue and help you work through it if you have access to one. But if it's reflux you'll need to see the doc for it.