I feel your pain. I tried to nurse my twins 2 yrs. ago & had every desire to nurse them for a year. They were premies & didn't have a real strong suck. They also had a bit of jaundice & were sleepy a lot. Long story short, I nursed my daughter for an hour on one side, my son for an hour on the other breast & then pumped an hour for a total of 3 hrs.. They ate every 3 hrs. so I was a milk factory; however, the kids were losing weight.
I had to go in to the drs. office for 3 weight checks & at 5 weeks old they still hadn't gotten back up to their birth weight! I didn't know they weren't getting enough. I did know my pumping was very scant but I just thought I was empty or not doing something right.
I tried the fenugru, the herbal stuff, double electric breast pump, hand pumping, lots of water, etc......I came to the realization at 3 mos. old that I would have to go straight formula. All was well. The kids fattened up & my breasts were relieved (after many clogged ducts).
Good luck but I think you've tried everything. People told me the more you nurse, the more you have.....keep pumping....I did it all & to no advail. Women are just made differently.