I have a slight heart murmur. Should I be worried? I was told about 3 or so months ago that I have a slight heart murmur. They said it was a level 1? So I don't think it is too serious. But today it feels like my heart is beating really really slow. But I

A. A heart murmur is nothing more than turbulent blood flow through the heart and can be caused by many different situations ranging from completely benign (vigorous flow through a normally pumping heart, or pregnancy) or more serious conditions such as valve narrowing (stenosis), leaking (regurgitation), or a hole in the heart. Murmurs are typically graded based on the loudness (grade 1-6) and the description can often give clues as to the possible cause. The only way to know for sure if a murmur is benign or more concerning is to have an echocardiogram done which will show any abnormalities that might be present. I would discuss this with your physician and consider this if you are really concerned.
Likely nothing.. I presume they said a 1/6 murmur, which is how we classify them. A 1 is very soft, very difficult to hear and seldom indicative of heart disease. You have probably had it a long time, but no one heard it (again, very soft). If they said don't worry, don't. A murmur is a sound, not a disease. They can mean a problem, but more are not. Ask your doctor directly, is it innocent?