Ive heard that story many, many times. Infact, it's nearly identical to mine. I can't say what to do, just that your problems seem to be consistent with the anxiety a lot of us here have dealt with. At first, I had the problem too. Constantly checking pulse rate, so scared I'd cry and get my boyfriend to do it.
Your test will show you are fine. When it does, you must accept it as true. What you're experiencing is terrifying, and I'm not gonna pretend it'll be easy to recover. But it gets better. Just remember to accept that you are fine, force yourself to accept it, when your tests come back normal.
Oh and stop checking your pulse. That's basically hitting a panic button. Every time you get the urge, force yourself not to. No matter what. It will be the difference between anxiety and overwhelming terror.