help!

I'm on the pill for at least the last four months, I've had unprotected sex alot since then, he has never came in me but we stayed going untill he had to pull out real quick so we aren't sure if anything is in or not I'm finished my pill now and am meant to get my period I've been finished my pill for 3 days and I've started to have something like a period but instead it's very small and it's brown, does anyone know what this means