An ECG will have revealed if you have had a heart attack, also a blood test will have shown something.
When I was 28 I had a heart attack and had no jaw ache, no pain on my left side, just a crushing feeling in the centre of my chest. I thought I was OK cause I didnt have any of the above 'commonly' reported symptons ( I thought that you were only having a heart attack if you felt shooting pains down your left arm) - Bottom line, never take chances with chest pain, whatever your age. By all means get a second opinion on the chest pain, but after the tests you've had I would rule out heart problems.
Also, a high percentage of patients who have sufferred a heart attack dont get any Jaw pain or left sided shooting pains. If this is your guide to deciding whether you are having a heart attack, you could be putting yourself in danger.