How to get more milk??

Melissa • My husband and I were blessed on November 19 2015 with our son Nolan! Currently pregnant with baby #2 👨‍👩‍👧‍👦
I've never nursed cause my son wouldn't latch on so I would pump and feed him the milk but I wouldn't pump at night and after a couple of weeks now I only get a very little amount of milk when I pump like 2-3 ounces after 20 mins of pumping, and now my son will latch on but he just spits my boob out after a min because he isn't getting enough milk... Is there anyway for me to increase my milk production and get it back to the way it was before or am i already "dried up" at this point.. Any advice is greatly appreciated I would love to be able to actually breast feed now since my son will latch ( and has a very strong suck.