Oh my I'm having flashbacks reading this thread!
Super huge hugs to you - it's such a hard time. I don't know if it's helpful at all, but there seem to be lots of us with similar issues early on who made it - I hope it can give you a little strength to go on.
Please do try and get help with the nipple shield. I know they're kinda frowned upon, but I dont' know that I would have made it very far without it. Like you I had perfect technique but was in serious pain. but it all came good once he was bigger. There is a knack to using the shields. I found that I had to work very hard to line them up with the nipple just so or else they didn't go on right. Also, there are different kinds. I tried 2 and one worked a lot better for me than the other, so if 1 is no good might be worth trying another.
good luck!