Breastpumping and breastfeeding

I have a two week old and I started to breastfeed him but he wasnt gaining enough. He actually lost weight so I had to start pumping to make sure he gets enough. I feel like I'm not pumping enough milk I'll say I'll get atleast 19oz a day 9oz from both breast sometimes less 1oz or 2oz. He drinks 2.5-3oz about every 3 hours. I never have anything to freeze and I plan on going back to work after I'm all healed and ready but I'll like to stash frozen milk to be ready for my mom and boyfriend. Is there ANYTHING I can do to help milk supply?? I pump 3 times a day morning afternoon and night and throughout the day he will latch on and feed and I drink plenty of water.