Man I have felt the same way. Whenever I'd discuss the symptoms with my friends, we would go down the list and try to find connections between the symptoms and other issues. At the time, we could make sense of some of them and what they appeared to be... thyroid, caffeine sensitivity, etc. But then I'd have an attack that would throw those theories out the window. My thyroid tested good, and I'd have an attack after two weeks of drinking nothing but water. (Just some examples, but this happened all year long with different scenarios..) All of this, of course, was before I accepted that the problem was anxiety.
My friends and I would start back from blank, and try to work through the symptoms and figure it out. We did this because I felt the dr's weren't caring and that I truly had something wrong with me. In moments of frustration, I'd make a comment like "They'll figure it out when they do the autopsy on me." -- Don't get me wrong, I was mad and frustrated. At no time could I ever say I was depressed about the situation. Throughout everything, I think I've done a good job staying upbeat and positive.
First off, don't google your symptoms. Google is not a dr, and doesn't know jack about you. Google will turn a sneeze into cancer. If you do feel the need to Google your symptoms - challenge what you find. After all, you have no problem challenging your own doctor's diagnosis, but we seem to accept Google search results so easily.
Hang in there, and don't let those symptoms get the best of you. Talk to your dr and listen to what they have to say. They know you better than you know yourself. (When in doubt, ask the nurse. Seriously. Nurses always seem to have more real world working knowledge of medicine and the body than dr's, at least in my experience)