Evita I know what you're saying. I have felt the same way, and only recently10 yrs into this, reallyhave begun to feel a little less morbid.
What I'm hoping is that your appointment will reassure you AND find a way to treat your problem, so that you'll soon feel as though a huge weight is lifted & that you're not going to die imminently after all. I imagine your life will feel much different once this gets sorted.
(Sorry this is so long; I don't have time to make it more concise.)
I, too, have that worry that any medication is going to make my condition worse. For a long time I had sort of a fear of medications, and it even took me longer than it should have for me to find the courage to take my heart medications when necessary. Apparently that attitude is common in depressed/anxious patients. I'm told there's a way in which we resist treatment. . .which always seems like bullocks, but that's what they say.
I wonder if a benzodiazepenelike valium or something to be used SHORT TERMwould be better for you. It would help with the constant anxiety and your sleeplessness. And they'd be unlikely to have bad side effects. But for some reasonI imagine because of their expensethe NHS seems reluctant to prescribe them. I have to get them for my MIL from the US because no doctor will prescribe them to her even though she uses them EXTREMELY infrequently.
I'm not sure the valium/xanax idea is so practical under the circumstances, but I wonder if it isn't a better possibility for you (?)