The problem with having health anxiety related to your heart is that cardiac symptoms and anxiety symptoms are nearly identical. Your constant stress will keep your HR up, and also cause dizzinees, weakness, and fatigue. If you had an echocardiogram and EKG two years ago, it's extremely unlikely that anything would have changed in that time. I know, because I just asked my doc about the echo, stress test, and Holter I had two years ago. She said at a minimum, absent other risk factors (high blood pressure, high cholesteral, etc) those tests are good for 5 years. I get all the same symptoms you do, and it's never my heart, though I would swear it is.