JJ, I really do understand how you feel as I'm in a similar place. I only have to realise that I have to walk somewhere and my chest starts hurting. All I can say is that the constant focus on my chest pain has begun to alleviate but only because I am now fixated on my dizzy head, twitchy leg and bunged ear. That says to me that it is anxiety - yes the pain is real and you can get spasms of the coronary artery through anxiety induced hyperventilation causing heart pain as well as worn out chest wall muscles but it is still an anxiety response and not an imminent heart attack.
I am telling myself that if things worsen then I will demand more tests etc but at end of day, constant reassurance is a very short lived thing and you are back to square one.
None of this is easy and I'll admit I sometimes have to skim bits of posts if there's something triggering in it, but I do believe that things can improve if we take time to breathe better, do some relaxation and just accept that we can't be certain. If you think about it, you didn't know before 100% of the time that you were 100% ok but you just got on with living. Living the way that we are/have been isn't living and I am determined that if I drop dead tomorrow that I will have lived today.