Pumping Help

I'm exclusively breastfeeding our 6 week old son. It has been going great. I pump when I have time, and can get 2-4 ounces. I want to increase my supply, so I can build a good stash. I want to finish my nursing degree and get a part-time job. Right now I am pumping if I know I will be away for a few hours. With my first, she was with me most of the time and pumping wasn't as necessary. Also, in emergency cases when I don't have enough breast milk stored, which formula would y'all recommend? I had emergency gallbladder surgery when my daughter was 7 months old and I was in and out the hospital for a week due to a gallstone being stuck in my bile duct. Needless to say she ran out of breast milk and had to drink formula which she hated. I had to pump and dump during that time. Also, my mother has to do 6 months of chemotherapy coming February and I want to be there for her as much as possible. Any advice would be appreciated.