L.W.
I had the same problem as you..only dif is I worked full time. My supply was gone by the time she was 5 months old..I ended up loosing the battle. :(
It was suggested to me to drink more water, and pump more often. I would wake up in the middle the night to PUMP..I would also pump before feedings. Seemed like the machine never got out as much as the baby could suck out.
I still lost the battle after being FT back at work after 2 months. I think you are doing all you can.
Just remember Formula is not poisen...its ok to suppliment with it if you dont have enough. I would rather have a happy baby on some formula than a grumpy hungry one :)
good luck