Period help!!

Truie • I`m crazy. A perfectionist. A trumpet player. And a hard headed hillbillie.
My period was supposed to start 3 days ago. Nothing has happend. I'm on bc pills. And haven't done anything bedroom wise in 3 weeks. Any ideas as to what's goin on? Can stress levels mess up your period? I'm just concerned for myself. Plz comment and help a girl out.