How wonderful that you're clean and sober, that's great!!
I guess being "reasonable" about one's health means that if something is wrong and you are concerned, you go to the doctor and get comfort from what they tell you.When you say that you "obsess" and your anxiety is "constant"..obviously this is not ideal or balanced or "reasonable". The internet is such a double edged sword. We can scare ourselves silly looking up symptoms. On the other hand, they can save our lives.
My advice is to stay clean and sober, keep eating more healthfully, and start weight training or running for exercise. That way when you focus on your body it can be with more enjoyable motives than making yourself crazy when your imagination runs away with you. You will begin to associate a raised heartbeat, etc, with getting healthy, rather than being worried.