pumping enough milk for my preemie

I have been pumping for ten weeks now since my son's birth...it is hard. My milk has greatly diminished. I have tried mother's milkplus and fenugreek. Now I am getting ready to start reglan. I know of the side effects but I want to do whatever it takes to provide for him nutritionally. I just dont want the supply to decrease after I stop the medicine. He is still too weak to suck and pumping doesnt express it like a human would. I am trying not to give up. It is so stressful with him in the hospital....I hope I can stay focused.