Hello Bannanon~Wow, your cholesterol, b/p and resting pulse is stellar, nothing wrong in those areas. Since you have had all the tests, and they have been "normal" I don't think I would worry too much. The sharp pains are more than likely muscular in nature, most heart related pains are not "sharp or stabbing" However, if you really are scared, then I would by all means see the cardiologist again, peace of mind is worth millions.
Another suggestion, if you do not see a chiropractor, it might be a good idea, sometimes when I have these sharp pains, my mid back or rib is out and he fixes it and I am fine. Also, "Costochondritis can cause these sharp pains, I would ask about that as well.
I'm a 62 year-old who has been very physically active all of my adult life. Heading into my late forties with a stressful job and and experiencing physical changes due to aging, I began to experience sharp pains in my chest also - very frightening, yes - but in my case evidently not related to a faulty heart. I've found that I have had good luck with understanding that my body cannot happily sustain the kind of physical and mental stresses that I put it to year after year....sometimes its good to "give it a rest" or try a new form (or level) of exercise that might reduce the level of redundant stress (with the resultant strains and nerve issues) that high-use body parts have to deal with. Try it -