There still might be hope for your girl. Did you see if she can undergo surgery? That helped my girl and others on this website. My girl's cancer never returned and her tumor was quite large for her size. She was diagnosed in February 2008 and operated on in May 2008. To this day, there is no return of the cancer. Also, I was giving her shark cartilage.
I hope you can get the help you need for your girl. If you live near a veterarinary university, I would go there to talk to them.
My sincerest regards and prayers for a recovery,
Carol