heavy to light

Audrey
Last month my period was unbelievably heave and this month it's really light like I think I'm done and I should have one more day left. My periods have always lasted 6 days. This has been happening for about the past 4 months. It will be really heavy, like leak through a super in an hour heavy. Then the next month it will be so light I think I'm spotting by day 3. Is this normal? (I'm not on any type of birth control.)