You are not actually having a period, you are having breakthrough bleeding which can be heavy.

Okay get this, the period you get on the pill is not a "real" period, you only bleed because you stopped taking hormones. The very first pills did not have a period week, and it is not necessary because the pill stops uterine lining growth. But this seemed unnatural to some women and a period was added!

So you forgot a pill your body says" ooops no hormone, time to bleed"

i was in the same boat as the above i missed one pill and i cam on my period,, it was only light a slight bleed... i understand now y i came on my period but will i have a a chance on becoming pregnant i have taken my pill back to back for 2 months, so will me missing a pill matter??