Angina pain but normal CT angiography.

I have been struggling with exertional shoulder, upper back and chest pain/heaviness with shortness of breath from last 6 months. Have gone through with several tests. TMT that came mild positive due to st segment depression, stress echocardiography that was negative, holter test that shows only sinus arrhythmia. Went for CT angiography to rule out blockage that came normal with 0 calcium score, but to continue to have typical symptoms. To give background, I'm 37 years old male, do not smoke or drink alcohol, vegetarian.Chelestrol total-167, LDL,125, HDL 33, TDL- 139. No high blood pressure instead it is on lower side e.g 105/68, 110/70. No family histrionics of early heart disease, but grand parents and father died due to heart attack post 65 years of age. Slim and BMI 19 My life has really detoriated, I feel handicapped coz I can't do anything and left with no energy to perform regular activities Please suggest what could be the cause as no one seems taking my symptoms seriously .