also, it actually doesn't sound like you don't have enough milk, especially if you're leaking into several breast pads a day. When you leak into the breast pads, do you feel the let-down (that's when the milk comes out in gushes). do you feel the same let down when your son nurses?
if your bb falls alseep on the breast, how long has he been feeding?
if he wakes up crying, maybe he has wind in his tummy, that's what happen to my girls. try to burp him after he wakes up from the scream. if he's still screaming, put him tummy down on your lap, & sway him side to side. if he calms down after you put him tummy-down, that means he has tummy pains. (usually wind) then sway until he calm enough for you to change position (maybe even 5 mins), pay close attention to if he has small burps. if he still cries after you change position, feel his tummy if it's cold, he has wind. then rub some olive oil (need thick oil) vigorously between your palms to heat up & put your palm on his belly button. rub your palms again if your hand not hot anymore. funnily enough, it works.
i also notice that when my bb woke up crying (she's now 3 mths old) after a feed, & then i'd think she still wants milk, so i give her breast or bottle, she'd suck for a bit & turn her head & cry & suck & cry, this means she's tired but want to suck, that's when a pacifier comes in handy.
pacifier are useful especially for baby is cries a lot. but use with precaution, make sure your bb fed, diaper changed & well burped before using.
(oops, bb wake up now. will post more suggestions later)