Kami, I am so sorry to hear this and prayers are going out to help strenghten your baby. I am in Illinois and my friends puppy was deathly ill, the vet opted to put hers to sleep to. She then called animal hospitals in surrounding areas to see if anyone had experience in the illness. She felt the vet was giving up to soon, so she found a hospital in Indiana. She said if they could get her pup to live a little while longer, that's what she wanted.
I've read where a lot of rescues have dogs with liver shunt and send them to certain vets with experience. You may want to call them for recommendations. God bless you, I can't imagine the pain of what you or others have to go thru, so my heart goes out to you.