Cash's 2 week check-up

Cash had his 2 week check-up yesterday because the Dr. will be out of town tomorrow. Everything looks great other than the fact that he isn't gaining enough weight. The Dr. wants to do a weight check on Friday, and if he isn't happy with it, we may be headed back to the hospital :(
Cash isn't really breastfeeding, I think it's because just as he was getting the hang of it is when we had to go back to the hospital for his jaundice treatment, and it wasn't really possible to breastfeed there. So, I am pumping as much as I can but also supplementing with formula. Because he hasn't been depending only on breastmilk, I've been slacking with the pumping and now I feel like my supply is seriously decreasing, which makes me feel pretty sad. I'm not giving up though, I'm actually looking into what I can do to bring my milk supply back up, so if anyone out there has any suggestions, please feel free to let me know!

*Update- Thanks to those of you who have emailed me with suggestions for my milk supply. I've been double pumping, more frequently and Cash even nursed today on both sides for the first time in several days. I'm going to try drinking a beer a day, continuing to pump while staying well-hydrated, and taking my prenatal vitamins again. I also sent Matt to the store to pick me up some Fenugreek.