Ok my periods always come on the first but this month it came on the 21 & im still flowing heavy y us that? I've really been stressed lately.

Many possible causes. Prolonged menstrual bleeding can result from many possible causes. You could have a systemic bleeding disorder (low platelets, for instance) to ovarian problems, to something going on in your uterus itself. Stress w/hormonal shifts can disrupt menstrual cycles also. Please see your family physician or gynecologist to investigate this problem -- which sounds like it's troubling you, be well.