Oh, I am so very sorry. You have done such a wonderful job of taking care of her and tried so hard. Just know that you did everything you could. And I am positive she KNEW you were trying to help her. Animals know our intentions.
One thing, if she is taking pepto bismol, that can (WILL) turn her stools black. VERY black. However, it also contains aspirin so it could increase any internal bleeding.
I hope she gets better.