Thank you for your responses. In particular, thank you, Gator, for telling me about how it was with you and H. I know I will have to make this decision, it is just a matter of when. It is so hard to know what her experience is, and I don't want to take even a minute of life from her if that is a minute she could enjoy. And I don't want to do it just because I am suffering to watch her. It is all just so hard to know. I have decided that when it is going to be, I am going to ask the vet to come to my home. She is always SO afraid at the vet's office---I don't want her last minutes to be there.
I am not planning to make any decisions until I see the vet. But truthfully, I am not sure about what the test results will accomplish. I have been doing a lot of reading online and I am convinced she has kidney disease. (but I will ask about thyroid). If we get blood results that confirm that--then what? I don't see how I am going to get her to eat, or get her to take the medication that would both help her to eat, and deal with any mineral imbalances, etc that she has. I might, with great struggle, get her to take a pill---but I can't prevent her from vomiting it back up. And I could put liquid med in her mouth, but can't prevent her from drooling it out. And what good does it do to put powders in her food if she can't eat?
I found a description of cat's with CRF that have a kind of seizure that involves just standing and staring. THe cause is probably a mineral imbalance---requiring meds. I also read that mouth ulcers can cause them to approach the food and then not eat---and if I remember correctly, that also means meds.
Anyhow, I greatly appreciate your warm support and understanding. I am so grateful for this site and all of you. (PZI-ers are the best!)