I Take My Birth Control Pills Around The Same Time

I take my birth control pills around the same time each day. I have unprotected sex with my fiancé. On Sunday I had light pinkish bleeding but it stopped after a couple hours. I stopped taking my pills to enduce a period to make sure I'm not pregnant. On Tuesday I got some dark brown discharge but very light. Is this possible sign of pregnancy? I know it's not an STI.