Re: Latch Issue
Well, it sounds like you know what you're doing as far as the latch. I'm sure you're waiting for the wide open mouth and allowing her head to fall back as if taking a bite of a big sandwhich.
I would definately keep changing up the positions to find something less painful. If you are having a powerful letdown, the position laying on your back with the baby up and down on your tummy helps slow the flow.
Using a gel pad (frozen) before and/or after nursing may help with the pain. If you think the baby is using you for a teether . . . my solution was to stop nursing, put the baby down and leave her to get upset. Before long she realized that biting down was stopping her lunch!!
Hope some of this helps.