Ok so I went to the LC yesterday afternoon, and the overall takeaway seemed to be that this is just the way things are and they aren't likely to get better.
She told me to do block feedings to reduce my supply and suggested lecithin as a supplement in case my ducts are getting clogged. We practiced latching a little, but I couldn't feel much difference between the good latch with her and my normal bad latches. She said the letdown pain I have in breast A while I feed the baby on breast B is inevitable and can't be helped. She said that when my supply is more regulated, then I wouldn't have so much achiness and sensitivity in the breast between feedings, and the letdown pain and perhaps overactive letdown will get better too. I have a hard time believing that because my breast is achy and sensitive even when it's just been drained, but I'm not sure how much of that is nipple pain. I was hoping for some kind of immediate relief, and failing that, hope, and I don't think I got that.
The LC also described what is necessary to cut milk from my diet, and I hate that idea. I don't think things are bad enough to require those desperate measures now. The baby only sometimes fusses at the breast, but doesn't fuss all day and isn't colicky.
I asked about nipple shields and she said they wouldn't help. I'd like to try them, but like you said, they shouldn't be used without guidance and support, and I don't feel I have that.
Sometimes I do have the tip of the nipple turn white. Not every time. And sometimes there's a crease in the part of the nipple where the side of the baby's mouth was, as if he's flattened it.
I guess my next question is how will I know when I should stop the block feeding and when my supply is not too much, not too little, but just right?