Hi Judy- very interesting question. You have mentioned several issues and I will address them separately.
1. Stress cardiomyopathy (CM)/"heart attack" - We see this quite often. Stress CM has several other names - "Tako Tsubo"/"broken heart"/apical-ballooning CM. It refers to a condition where (mostly) women develop chest pain after suffering some sort of emotional or physical stress, and the EKG and blood work suggest a significant heart attack. But during angiogram there would be very little visible coronary disease. The heart function would be moderately diminished, and the tip of the heart (apex) takes on the appearance of a bulged out balloon -- it looks like a Japanese squid urn (Tako Tsubo). This condition is overwhelmingly benign, meaning that most patients recover over short period of time (weeks to months) with FULL return of heart function. We don't know how to distinguish stress cardiomyopathy from a "real" heart attack, where there would be full blockage of a large coronary artery, so we do an angiogram in every one of these cases to define the coronary picture.
2. The second episode you describe one month ago, where there was +chest pain, +troponin but no "Tako Tsubo" and no major blockage, might be a different entity. You might have also hit upon the key already -- MICROVASCULAR disease. This refers to tiny arteries that actually to the work of feeding heart muscles. They are just as important as the large vessels visible on angiograms, but we cannot usually assess them by angiograms due to the size. Micoravascular dysfunction is more common in woman, so called "Cardiac Syndrome X". A good stress test might be able to confirm that during physical stress your microvascular coronary systems might be unable to keep up with the oxygen demand. A heart PET/Stress scan might even be able to measure the abnormal rate of blood flow into your heart muscles.
In summary, YES, it is possible to have a "heart attack" without permanent heart damage, and YES, tiny vessel disease might be the key to your recent episode. I recommend continuing a healthy life style, reduce stressors (can affect microvascular function greatly), and consider taking a long acting nitrate such as isosorbide dinitrate IF you are having frequent episodes of chest discomfort.
Very similar story here. I never recovered so mine was not so "benign". Best of luck to you.