All of your findings on echocardiogram are not rare. They are to some extent abnormal and should be monitored over time.
Sometimes when valve lesions are on the borderline side, or sympotoms seem out of proportion to the findings we do exercise echocardiography to examine the findings under stress conditions.
The fact you can run the extent that you do and the lack of symptoms compared with the symptoms you experience with lifting, may be more related to strength conditioning of those muscle groups.
Yearly exercise testing with particular attention to your capacity to exercise may be of help in detecting changes in your cardiopulmonary fitness over time.
hope this is a start.