I, too, had to EP due to latch issues and other issues. I AGONIZED over stopping...even tried domperidone (a prescription), power pumping, fenugreek, you name it to get supply up. Eventually, though, my supply dwindled down to about 4 ounces a day...which so made it not worth it. Even then, I agonized over it. However, once I stopped, I have been so much happier. Being hooked up to the pump sucks. I stopped at about 7-8 weeks. I don't think LO noticed, but due to supply issues I have always had to supplement.
One thing I did do, though, was to save about 4-5 ounces a day and freeze it. I have read where even as little as one bottle a day can help their immune system. I now probably have enough in the freezer to give LO one bottle of BM every day for about a month, but as of right now he is just on formula because the doctor switched him to Alimentum for babies with sensitivity to milk proteins and it has been working so well that I don't want to disrupt anything by giving him BM again. I have read where their immune systems are at their lowest at about 3 months so I may start trying to give him some more BM when he turns 3 months.