I don't think her weight is unhealthy-- I know that during certain times of the year BPs can lose some weight from feeding strikes just like this, and it isn't something to be extremely anxious about.
And yeah, maybe try again w/ rat pups! If you can manage to get her on them it'll make everything a lot easier. Just try to do as much as you can to reduce her stress (ie. don't handle her for a few days before you feed her. I've also heard that putting more things in the tank like fake plants and wood can make them feel more secure