it sounds to me like you are having premature beats, and maybe Even going into a irregular rhythm sometimes. The premature beats aren't that serious, and the irregular rhythms can be treated with medications. You may need to go back to your doctor and request a 30 day event monitor. This is a monitor that you wear for at least 30 days. With these monitors you have to push a button on the monitor to make it record when you a feeling something you want recorded. because sometimes patients do wear holter monitors and nothing shows up on them. That doesn't mean that there is nothing wrong it could just be that you didn't have any symptoms while you were wearing it. Their are also other test you can have done to check your heart out. This is something you want to stay on top of, but you also don't need to get too worried about it. Stress
and worrying is a major cause of heart problems.