It may be helpful to request a copy of your ECGs. You can then take them for a second opinion, simply outlining your symptoms and not go into what they "might" be. Good luck!
You said your ekg looked the same as a previous one, so no need to worry. I would put much more faith in the fact that all your other tests were normal. A ekg can change from one minute to the next. I've had so called abnormal ekg's for 20 years but they are normal for me. I do have one question, you said you have previous heart issues, but all your tests were normal. Just curious what issues you were having.
You are youngish and have had many, many tests of your heart, all indicating that your heart is generally healthy.
If you have taken stress tests and have not had to stop the tests early due to shortness of breath, the odds are *great* that the shortness of breath you report is NOT related to heart disease.
In fact, most of the symptoms you report, such as lower back pain, transient high blood pressure--in the absence of other known, genuine heart symptoms--have nothing to do with heart trouble.
You do not have to worry about 'misleading' your doc. When it comes to hearts, most capable physicians, especially cardiologists, can capably evaluate test results in light of a patient's history and appearance.
I worry that you may be developing something called a cardiac neurosis, which you can google. It is treatable, and I would suggest that you consult with your cardiologist about looking into that possibility.
Of course, weight loss and a medically-approved exercise program would be an excellent goal, as well.