I agree with the previous posters that looking into thrush treatment and a prescription for Dr. Newman's All-Purpose Nipple Ointment wouldn't hurt.
I just wanted to mention that my son had a "disorganized suck" and spent lots and lots of ineffective (painful) time at the breast in his first couple of months. Time and practice did help him, but we saw marked and immediate improvement when we took him to a pediatric chiropractor who adjusted the parietal bones (sides of the skull) that were probably giving him a headache. I have no idea if your LO has any sort of alignment issues that could be affecting the willingness or ability to suck properly, but I wanted to mention my own experience in case it sparks an idea. (I thought I was crazy when I took him in, but I had no other resources left, and I was blown away to see how quickly things improved. It still took a couple months to get everything "right," but the immediate difference was striking.)
I'm sorry you're going through this.
If there's any way you can tolerate keeping her at the breast, though, and avoiding EPing, I'd do it. I ended up EPing for my daughter (not because of pain but because she couldn't latch and transfer milk due to my anatomy, and by the time she perhaps could have, she was unwilling despite all my efforts.) I would try for more hands-on help if you can. It's expensive, I now, but so is EPing, and if it's better when you have assistance, that's a really positive step.
Kudos to you for keeping going through this and for being willing to admit that you hate it right now and need help. All of that is brave.