Hey man, thank you for your post. I am going through the same thing currently. Health anxiety and hypochondria are nothing new to me, been bouncing around from one life threatening illness to the next for years.
After reading an article about the disease, I now have the same symptom(?) issue as you're describing. Strange feeling in left arm and hand. Feels like it's hard to flex fingers, is kind of shaky/trembling, and just feels "odd". To be honest, I'm probably not going to even bother seeing a Dr, as I simply can't afford the time and money spent bouncing around for consultations and tests in my life right now. Been there done that.
If we can put this into perspective, we know that someone who was really suffering from this disorder most likely would experience a complete failure to accomplish the tasks you mentioned. An inability to lift a cup, or put it their garage door code. It seems to me, in my limited research, that these kinds of disorders show their face and you wouldn't be on the fence about whether it was a perceived issue or something real.
It's no different than when I was sure I had HIV, because I developed some rashes after a questionable sexual encounter, or was convinced I had throat cancer because of a swollen lympnode in my neck. I don't think I need to tell you that the outcome was benign in both cases.
Keep your head up my friend!