You can get your milk back. It will only take a little determination. It can happen and the sooner you start, the better. Drink lots of water and keep taking your prenatal vitamins. Get that baby on the breast and nurse, nurse, nurse. You two will get the hang of it. It may be frustrating for him at first, but persevere. I know there are special feeders that you can use that run a tube to the nipple so baby can suckle and get milk at the same time in situations like this which should help to ease any frustration he has while providing you the stimulation you need to begin producing. Maybe contact La Leche League to get more info on this, but in the meantime, offer him the breast first at any feeding and let him try it out. Remember, the more you let him suckle, the better your chances are. Try to stay as calm as possible. Anxiety can have a VERY detrimental effect on milk production. Just sit comfortably with him nursing, breathe slowly and visualize your breasts producing milk. I know it sounds weird, but it works. I've made it work for me during times of need (like when I had to take Sudafed and my milk supply suffered). Close your eyes and visualize gathering your energy in your chest and gently pushing it out through your breasts. Again, don't knock it until you've tried it. It works.
Here is an example of how possible this is. I was adopted. My mother and father had lost two babies (one at birth and one much earlier) before adopting my older sister and I. My mother was actually able to breastfeed me because she stuck it out and stayed calm. She had been pregnant twice and delivered at term once, and three years later was able to nurse me as a newborn infant even though I wasn't hers.
You can do it! I have faith in you! :) Best of luck!
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Sorry to edit the minute after I posted, but I just reread your question and I wanted to tell you one more thing. Baby is always a far more efficient milk retriever than any pump. He'll get way more than you've been able to pump. I guarantee it. Give him the breast that has been producing first in a feeding so he can get used to the idea that yummy milk comes out of these, but make sure that you switch to the other breast every time and let him nibble on that one as long as he like. Again, best of luck!