Continued prayers for your girl.
The teaching hospital here has greys in residence (I don't like it but they are well cared for) as blood donors. Is there a teaching hospital near you? Maybe it would be worth a call to see if you could get the blood there.
I would be taking her to the vet. She will need a wellnes, first visit in any case. There have definitely been times that my vet has known that the visit was for my peace of mind as much as it was for the regular check up.
I think Duncan41's suggestion is good. I know my vet had me set up Aquitaine's treatment plan with an internal medicine specialist and then my vet manages the regular care and tests.
Keeping Legs in my thoughts and prayers. I hope you get an answer soon.