I am very sorry about your puppy being so ill. I do know that there are different types of liver shunts and the treatment depends on what exactly is going on . On Monday you will find out more and what the tests show. Is your yorkie real tiny? I have heard that very small Yorkies are more prone to liver shunts and health problems.
Have you contacted the breeder where you have got Molly? How long have you had her? This is very heartbreaking.