Ongoing left sided chest pain for 4 years

Hi Doctor, I am a 25 year old female. For around 4 years now I have been having left sided chest pain that comes and goes. Sometimes I might get pain 2 days in a row and sometimes I might not have an episode for weeks. It comes on quite suddenly and is quite sharp and stabbing at first then turns into a more dull ache. I can feel it in my back and under my left armpit at the same time & it normally lasts from 2-5 min. The pain occurs at rest and does not get worse with exercise, and doesn't get worse with breathing in. I have had a few tests done including an EKG and CT chest scan 4 years ago when pain started, and an echocardiogram 2 years ago which all came back normal. (I was 22 weeks pregnant when I had the echo) Is there still a chance this could still be heart related? The pain always comes back and I'm at a loss as to what it might be. Does a normal echocardiogram rule out most cardiac causes for my pain or should I get further testing? My grandfather had angina and died from heart attack in his mid 50's. I also have a history of anxiety. Some advice would be greatly appreciated!