If he cries for more milk, you can make an extra 10-30ml to see how much he drinks (and won’t spit up or vomit after that) then you will know how much more to increase. Babies are smart so they will push out the bottle when they are full. You can feed on demand, if he cries for milk = feed, don’t need to strictly be 2.5 or 3 hourly. All numbers on the tins and webs are all based on average, no need to strictly follow it as all babies intake are diff. 😊
Try giving him 10ml or 30ml milk more until he fervently reject his bottle, then see how much he can drink. Even if he needs more,he can't if his stomach can't store it. you just have to feed more frequently then.