About this time my DS and I had to go to a lactation day stay. We found that he didn't have enough nipple in his mouth; and that now his mouth was stronger our bad attachment was doing serious damage. It seems counterintuitive, but try and get as much nipple in as you can, especially the underside part.
Feeding lying down can help with the pulling, and if you give her something else to hold she may not scratch so much.