increase supply?

I work full time. I pump 3 times are work, usually getting 4oz out each time... sometimes 4.5 oz, but not consistantly. problem is, my baby eats 5 oz every 3 hours while in at work. She eats 15 oz total, I pump 12 oz total. I can always get that extra 3 oz at home, either late night pump or morning pump. I really want to consistently get 5oz out every 3 hours line she eats, though. I can't power pump at work, but i squeeze my breasts until they are all dry when pumping. I nurse when I get home, and throughout the night. I drink enough and eat enough. what else can I do?