Have you been tested for hypothyroid? It's a fairly treatable condition so if you're really that concerned, a simple blood test would reveal the answer.
You don't have to apologize for your posts. A lot of people deal with these fears and it can be a good sounding board. I don't know if you ultimate goal is to get past your anxiety or not, but if it is, it's going to require a substantial effort on your part, including giving up things like googling health information and indulging these kinds of irrational fears. While I'm sure someone out there has died due to an untreated thyroid problem, I'm sure that's unlikely and not a fear worth wallowing in. So whether you do have thyroid problems or your symptoms are all attributable to anxiety, assigning catastrophic meaning to them and overreacting fearfully to them is causing them to worsen. This, as health anxious individuals, is what we must combat.