Breast pumping, HELP please.

My daughter was born 10/10 due to an incompetent cervix. I wanted to breast feed but I'm pumping instead since she's in the NICU 3 hours from home. I drink between 80-90oz a day, I eat oatmeal a couple times a week. My supply increased greatly after she was born until this past weekend. I went down to visit my daughter and didn't think I'd be staying and ended up staying from Saturday morning until Sunday afternoon. I only got to pump 5 times in that time period. & only had maybe 45oz of water now my supply is so low. I went from getting 10+Oz a day to 5oz in 2 days. What can I do? Help please!