Pumping advice

Hey all, 
I've recently returned to work and it doesn't seem like I can pump quite  enough to replace the milk my LO will drink during daycare. Is anyone working part time and breast feeding/only pumping for bottles? Any advice? I know I make enough milk because my baby has plenty of wet diapers and is gaining weight appropriately but I'm not a very good pumper. How much do you get out when you pump?