For one thing, your heart rate will depend on how much exercise you get. When I began exercising (i'm 19), my resting heart rate (when I wake up) was 85, and after 3 months of jogging 3 days a week for 20 minutes, my resting heart rate decreased to 72. You doctor may have been telling you that your heart beat was irregular, and not necessarily your heart rate. If you feel a "flutter," it may be an indication of some heart problem, but don't worry if your doctor didn't seem worried.