Dark Brown Period on birth control

I’ve been on birth control pills for at least three years now, maybe more, and have taken different kinds of pills through those years. Currently, I’m taking Apri, and I take it so that I have a period every other month. Last time, my period was very very light. This time, it’s barely a period, just dark brown discharge. Is this normal?? I do have unprotected sex with my boyfriend regularly, but I take the pills religiously and he always pulls out so I’m assuming I’m not pregnant?