S.C.
I read all the material I could find on breastfeeding, attended lactation classes and had three lactation specialists in my room after giving birth to my son. What no one prepared me for was the fact that I may not be able to actually produce milk at all. I pumped at the hospital, but had to immediately begin supplimenting with formula because I wasn't producing anything. It took more than a week after my delivery to experience the breast fullness and that only lasted a day or so. From the day my son was born, I tried pumping every two to three hours, but it would sometimes take an entire day's worth of pumping to produce even three ounces of breast milk.
My menstral cycle came only three weeks after delivery and what little milk production I had stopped. I recieved a multitude of advice from well intentioned people all encouraging me to keep trying, even after the well ran dry. No one seemed able to accept that my body couldn't actually produce milk.
There are a number of products on the market claiming to encourage lacation and they might help. What's most important, however, is that your baby is getting the calories and nutrition needed to survive. Check with your pediatrician - they may suggest supplimenting with formula at this time. But don't beat yourself up if you have to do so. You're already giving your baby your best effort.