Some people that are successfully breastfeeding will say that no one should be feeling any guilt that truly tried their hardest. I think this is nonsense. The overwhelming feelings of motherhood can push any of us to feel "guilty" about any of our perceived "failings" even over things completely out of our control.
This morning, I fed my baby his morning bottle on the couch as I always do. It's our special cuddle time every morning. He is almost 10 months old now so he can hold a bottle in the high chair just fine, but the first of the day he still gets held like a tiny baby in my arms (with his long legs hanging out of my lap!). Sometimes, even in these special times with him gazing up into my eyes, I can be overwhelmed by a grief/guilt combination, as if I could have done anything about being hospitalized for nearly 2 weeks when he was a week old, or kept up a pumping supply with 103 degree fevers.
The guilt and grief was much worse with my first son, when like you, I just had no supply no matter what I did, took, swallowed, pumped, drank, ate, meditated, etc. He is 8 years old now, and I'll be honest, I'm still occcassionally bothered/reminded of that emotional pain.
You couldn't have tried any harder without most likely putting yourself in a mental ward. A lot of us have been there. It does seem that some people are better able to rationalize the fact that their very best efforts did not yield the result they wanted, and moved on. The lack of true inner peace over the issue is upsetting. And I firmly believe that the internet makes it worse. I love being able to come online and chat/read threads from moms all over the world when I am so lonely, but it too often comes at a price of reading some very hurtful things.
I can't promise you the hurt will ever go away, but it does fade considerably. Once your little baby starts hitting more milestones, smiling and laughing more, and even starting on solids seems to help. Take care.