Good point about the teething, that often puts them off any type of sucking whether from bottle or sippy cup or booby.
I have heard (though I am not an expert and at the present time can not recall where I heard, though I believe it was from another BWer on here) that if they never drank milk again, they'd likely be okay as what you need from dairy, particularly milk: calcium, vit. D., fat, etc. Can be gotten in enough other places that it is not as necessary as we might think.
Could be teeth, could be a phase where she isn't keen on the taste, could be a number of things. You just keep offering and try to up her intake of yogurt or cheese or other sources for those same nutritional needs.