He nurses.... not great. Usually a pretty shallow latch, but he just can't maintain a deep latch. The therapist said he mostly chomps, not sucks, and some days I can feel that; some days I can't. I think my nipples have just become so used to it that I don't feel the pain any more.
The therapist and an LC both recommended I use either a Soothie paci or my finger for suck training -- not to just let him suck on (although we do let him use one in the car if he's fussy, otherwise we'll never be able to go anywhere). Basically, we let him suck on it then tug, forcing him to maintain a suction to keep a hold of the paci.
At this point, I've spent 4 months visiting my ped, 2 LCs, 3 therapists, a chiropractor, and 2 ENTs (one of whom clipped at least part of his tongue tie). I have one more doctor to see next week (craniofacial surgeon), and then I'm done. I've pretty much given in to the fact that this is how it's going to be. It's gotten slightly better over the months, and I'll just have to hope that it keeps getting slowly better. In the meantime, I guess I get to suck it up.