Heart Murmur

I used to get minor heart pains a few years ago, but up until last year, they became more frequent and the pain has gotten worse. I went to the doctor last summer and he told me for the first time that I had a heart murmur. Since then I have been to 2 different doctors. One sent me to have an echo then the second doctor had me wear a heart monitor for a week. Both test showed up "normal" for my condition. Both doctors work at the same clinic back in ontario and I now live in alberta, canada. For some reason I am not totally convinced because there are times that they get soo bad I cry. They dont last for more than 30seconds, I dont smoke anymore, I dont exercise because it only brings more stress to my heart and the doctors say that the cause is stress. My mom's cousin has a heart murmur and had heart surgery. I would like some opinons to see how I should handle the situation now. I cannot predict when I will have a heart pain and sometimes I get short of breath, heart palpitations.