What is EP? Does that mean exclusively pump? I'm not sure how long a person could keep up a milk supply by pumping only b/c even top of the line pumps won't be able to express as much milk as a baby would by sucking.
When I was bfing, I had tons of milk until I went back to work and had to pump, that's when my supply dwindled. I had a medela pump... the one that is right under the hospital grade pump, can't remember what it's called. I took reglan for a bit to boost my supply and continued bfing until ds2 was 27 months. However, with ds1, my milk never came in at all. I tried really hard to bfeed, but it just wouldn't work and I have no clue why to this day. I was so afraid that would happen with ds2 that I started pumping when I was still pregnant (as soon as I was 37 weeks so that I didn't risk preterm labor). I did not pump much, just put the pump on for a few minutes a couple of times a day and stop pumping before any milk came out b/c I didn't want to lose my colostrum. I don't know if that is what did the trick, but my milk came in right on time with ds2.
One way I have heard of to really boost your supply is to start pumping on one side while baby is nursing on the other. This mimics twins so the body produces more milk, but you have to start it right away. Probably within a couple of weeks, I would say. My sil did this and she was like a cow for quite a while. She got to a point where she could just hold a bottle under one breast while her ds nursed on the other and she would get 2 -3 ounces just from leakage!!! She also had bfing issues with her ds1 and was trying really hard to prevent that from happening again. She has inverted nipples which prevented her ds from being able to latch well, and she lost her supply when he was 4 months old. She wanted to make sure she did everything she could to maintain a supply with her ds2. However, she ended up stopping bfing when he was 6 months old b/c she went back to school and all the pumping was just too much but it took her forever to completely dry up.
Good luck! I hope whatever you decide works out really well and that you are able to bfeed/ use breast milk as long as you and baby want.