Welcome to HCM
We understand your concerns
I went through your description. I suggest you not to worry too much. Normal heart rate
for a young adult in reasonably good shape is always between 65 to 90 per minute. This rate could become almost double during peak exercise periods. Because heart needs to pump more and more blood to every cell of the body at the double speed than when the body is resting.
In your case the heart beat of 200 to 225 is not so normal but not unusual. Your EKG and treadmill test also shows nothing is wrong. Therefore, stop worrying about this and enjoy the life.
Hope this clears your doubt. Available for further clarifications.