If all of your tests are fine, have you consider other things that may be causing your chest discomfort. GERD, Anxiety and many other disorders may be the culprit.
have you had a medical screening exam by your PCP to rule out other causes besides cardiac?
I hope you get to the bottom of you problem and that all is well.
Meanwhile do look at reading in the GERD and the Anxiety Forums.
and Heart/Cardiovascular Disease. "She Stood in the Storm & When the Wind Did Not Blow Her Away, She Adjusted Her Sails."