nipple shield

We started using a nipple shield bc my nips were terribly chaffing and raw. It helps a lot! But now my son is having a hard time latching on without it. I've tried widening his latch but he only suck on a nipple and he has a pretty strong hold, it's so painful. Does the shield slow down milk supply? I hear that with abnormal latch the baby's saliva gets the glands and help produce more milk. I feel like my supply is low bc of the nipple shield. Any tips or comments on weaning him off or producing more milk?