I just want to offer a word of encouragement to you. My BP just recently came off her own 9 month fast. I know how frustrated you are.
Definitely get a scale. They are cheap. And keeping track of weight was one of the stress relievers for me. A vet visit also made me feel better. My girl lost almost no weight over her fast.
She finally started eating again 3 weeks ago and I just fed her tonight. :)