Doctors would normally not miss out a physiological murmur (a normal and insignificant murmur) from a pathological one. When two doctors have given you similar finding, you must start believing at least one of them. If anyone had even an iota of doubt about the nature of the murmur, surely they would have suggested certain more investigations including an echocardiogram. However, a colored echocardiogram would give you a definite answer and would be able to certainly differentiate between a normal heart and a heart with some pathology that is causing a heart murmur. Please undertake this investigation at the earliest, otherwise you are liable to land up with what is termed as ‘cardiac neurosis’. You may also like to get your hemoglobin and thyroid levels checked as anaemia (low hemeoglobin) and thyrotoxicosis (high thyroid hormone levels or the sensitivity) are leading causes besides young age, anxiety, pregnancy, fever, and other causes of hyperdynamic circulation. Already the pathologic nature of the murmur has been ruled out by the clinicians of which there are different other reasons.