Pregnancy scare??

So i had sex on friday, he took a break (didnt bust, so he says) and took the condom off and finished on the ground. No where near me! But two days after that on sunday i started my period but it was very light and it lasted about 4-5 days. But whats scary about it is that it was lighter then my normal flow. Implantion pregnancy i think is a thing i read on the internet, 6-12 days after sex you can bleed very lightly for a short amount of time.  Im scared that this is a sign of early pregnancy!! Help !!