I can so sympathise with you

It is so tiring so good on you for sticking at it.
I changed feeding to one side only each feed, so each time I fed I would empty one breast, and then express from the other to ease the discomfort. Feed from the other breast next feed and so on. Your body will adjust the supply to meet the demand so eventually you won't need to express from the side you didn't feed from.
This seemed to work for me so you could give it a go.
Have you contacted a La Lech League representative? They may have some helpful suugestions for you.