Your body will regulate itself, it may be regular for you to be irregular, everyones cycles are different, most fall in the "range" of 28-31 days many do not. As long as your not bleeding excessivly or having increadibly unbearable pain its ok.
most girls do that from what i hear,,i think its just your cycle.. it wont be like the first week of every month.so no nothings wrong with you.. its normal