So what would your advice be to me? S
Kind of what sixpack stated above, doctors know their jobs... you go to the doctor because you respect their opinions and analysis of your condition, otherwise it is a fruitless effort. When the doctor states you are okay after running tests, then you have to accept the fact that they have hard evidence to suggest nothing is wrong.
You are here because you are still worried, which means you do have come face to face on how to control your anxiety and to make it stop controlling your life.
Have you talked to your doctor about anxiety? Maybe getting some professional help and someone to talk with to see if their is a root issue at hand?
To be honest, I posted a thread here a few days ago explaining it, but about 5 different things had to come together for me. All of them changed my life in a different way. I had everything from God, to a wife, professional help, accepting the fact I can't control everything and prevent everything, and a little bit medication to help get me started.
It is a constant struggle because that little voice of doubt will always be there, it is only you that can ignore it and put it aside and trust that everything is okay.