How much expressed milk does he need

I use to give my daughter 4oz at a time, if she drank it all I’d offer a little more but started with 4oz, because I didn’t want to waste any of my pumped milk

You could pump for 30 minutes or if you’re like me and produce just enough I pump until nothing else comes out and if you have more than what you need freeze it and save it you never know when you might need it you could get sick and need medicine or an accident can happen and you can drop a bottle full it’s just good to have backup milk if you can produce enough personally I don’t produce enough to freeze any

The thing is I am an over supplier, I donate to local hospital so I can pump loads, when give bottle he usually has 160ml of breast milk but earlier he had 170ml and still wanted boob after as he was starving. I try pace feed him the bottle

He might not want to latch because he’s hungry it might just be a comfort thing definitely if he doesn’t use a paci my baby is like that I’m basically his human paci lol definitely cuz it’s not as easy for babys to self soothe as people say/want them to and a paci is how lots of baby’s (definitely formula fed) soothe themselves