When i pump my breasts am i suppose to give everything i pump out to my baby?

This may sound dumb but I have no idea if my baby is over eating or isn't getting enough. This is my second baby and I did breast feed my 1st but I hardly made milk so I gave her formula most of the time plus she didn't latch on. With my son which btw is 3weeks today did latch on and I pump and also give it to him in a bottle. The thing is when he's latched on idk how much he's drinking and he's not one to let me know when he's full he just continues sucking using me as a pacifier :\ at night its a nightmare I feel like he wakes up constantly to eat! When I pump I pump different amounts all the time sometimes I make 3 or 4 oz other times 1 or 2 on each boob. I've given him different amounts to see if he finishes everything and sure enough he will. At 3wks I don't think he should be drinking 5oz (when I make that amount) he does tend to throw up a little but idk if its cause I over fed him or if its just normal. He usually eats 3 or 4oz of breast milk and if I can't breast feed him in public I give him 3 oz of formula. How much am I suppose to give him (breast milk) am I suppose to give him everything I pumped out from both boobs or just one every 2 or 3hrs?