hmmm. sounds like you might need a trouble-shooter LC... Some have great reputations for solving seemingly intractable problems.
Anyway, sorry I can't actually offer any advice - what you describe sounds very much like my son. Was told over and over that attachment was right etc etc, but it really wasn't. I finally ended up using sheidls for nearly 2 months, then at around 11 weeks he just finally was able to latch on without squashing my nipple. One of the LCs I saw said he had a slight TT, but didn't think it would affect feeding. Was told my GP etc that it didn't need clipping. I suspect it actually did, and he couldn't latch properly till his mouth was much larger.