help!

Morgan • appa-latch-uhn. happily engaged. a badass aquarius who loves the colors orange and green.

so, I am on birth control, but I am not too trusting of it. I never miss a pill or anything like that. This month, I only got my period for about 5 hours. I googled it and the only thing that came up was "implantation bleeding". How probable is it that my birth control failed??