Exclusive pumpers?

I am EBF right now and I want to switch to pumping. I'm just having so much trouble with the latch & getting him to eat enough. He keeps falling asleep and nothing I do will get him to continue eating and then he's hungry again 30 min later. This topped with LO being colicky has me at my wits end. I want to start exclusively pumping & maybe just BF at night and would love some advice. I've noticed when I pump I'm only pumping ~2 oz each 2-3 hours however LO eats 3 oz every 2-3 hours. How can I pump more each time? & how can I start a freezer stash without having to pump hourly? I'm new to all this & would love some pointers. Thanks!