((((Michelle)))), I'm so sorry you are having supply issues. That is probably the most stressful thing for a nursing mother.
Are you sure he is only getting half an ounce? If you are pumping to tell, that is not a good indicator. If you haven't already, try doing before and after weights on a medela babyweigh scale - most IBCLCs have this type of scale available. You can see exactly how much he took in this way.
There a lots of things you can do to boost supply. The best is to nurse, nurse, nurse, and nurse.
Fenugreek is good, also try mother's milk tea. Oatmeal works for some women, some have had really good luck with wheatgrass juice. If none of those work, you could ask your health care provider for a prescription for Reglan.
How is your bleeding? If there was a bit of placenta retained from the birth, your milk supply will suffer. The biggest indicator of this other than low milk supply is prolonged bleeding and large clots. I actually had this problem after Eva's birth. I was passing extremely large clots and at one point what looked like placenta. I ended up having a secondary postpartum hemorrhage and uterine infection before the nurse at the OB's office actually believed that the bleeding I had been calling about for weeks was serious enough to be evaluated. *rolling eyes* My body ended up passing it all on its own and within 4-5 days my milk supply was wonderful. Sometimes you will need a D&C to take care of it if your body doesn't do it on its own. Retained placenta isn't terribly common, but it is worth mentioning.
I hope things improve soon.