I'm so sorry
. I hope you get conclusive answers and that your girl will be okay.
Liver shunt is not really my area, as neither of my babies have had it, but there are some very helpful folks here who can help and offer support, in terms of testing and diet suggestions. These are things you could print off and then discuss w/ your vet, who is probably already on top of everything.
Keep us posted. Good thoughts coming your way.