Hi,

If your nipples are damaged and blistered there is a problem with attachment - even if the midwife can't see it! She should have taken your concerns more seriously. There seems to be a lot going right with your breastfeeding. Sounds like your baby is thriving and getting plenty of milk.
This will pass. (Even as an experienced mother - my 3rd daughter sucked up a big blood blister on my nipple - I fell asleep whilst feeding her and she slipped)
Seeing a Lactation Consultant is a great investment in getting breastfeeding off to a good start. Let us know (roughly) where you live (or PM me) and we can help you find som-one.
A nipple shield may offer temporary relief - but you need to get to the root of the problem