hi! I'm on birth control and I've been on it since February. I have sex maybe attests 3 times a month. The last time I had sex was around July 16t and I haven't missed any pills. My period was due Yesterday and all I experienced was a little blood when I wiped and brown blood. I had my wisdom teeth pulled Friday and started antibiotics the same day. Why haven't I received my period? Is it normal for it to skip months with out me being pregnant?