I went back to work full time when my daughter was 8 weeks (all that I was allowed under disability). I would feed her on one side and pump the other in the morning (every morning, even if I was home, to help build up my stored supply) and then pump once at work and then feed her at night.
(In New Jersey it's required that your employer provide an area with a locking door to pump, although it is not required that you be paid for the time you are pumping, not sure how it is by you.)
I continued this until she was about 13 months and completely on whole milk. It is a commitment, but I felt it was absolutely worth every minute!
To sort of go along with your other post, I never needed to supplement with formula when I fed her, but my stored supply was somewhat lacking, so my MIL (who watches her while I am at work) mixed 1-2 oz of formula with 4-5 oz of breast milk for a couple of her mid day feedings. Since it was such a small amount, I don't think my daughter even noticed that it was mixed in. Also, I rarely had "wet nappies". Your body will grow accustomed to what your baby needs and adapt.
Good luck with returning to work. It is hard at first to leave your little one, but every day got a little easier!