I Am A 50 Year Old Woman With A History

I am a 50 year old woman with a history of High total Cholesterol, low LDL high HDL and Tri's extremely high. I do not do well on statin drugs, as I have tried Crestor, Lipitor and Tricor, all of which give me awful side effects. I have a family history of Arterial Heart Disease, my father passed at age 48 of M.I. My mother 73 (alive) has two arterial stents and a pace maker. I do not smoke, I do not drink, however I am overweight at 225lbs at 5'3", and live a very latent lifestyle. I recently had a cardiac work up EKG, tread mill stress and echocardiogram. All of which was normal. 7.5 minutes on the treadmill and valves are working as they should. My concern is my arteries, and my question is How and what test determine if I have any plaque buildup and/or if my arteries are diseased? I am experiencing lightheadedness, (not SOB, but not feeling like I could walk for more than 10 minutes with out feeling lumbered. Thanking you in advance for any suggestions you may have.