Working out pushing back period?

Okay, so, since I was fairly young, I was a swimmer. I always remember my mom telling me that working out pushed back your period. I've been pretty steady for almost two years now, and dropped swimming about a year ago. I was pretty inactive for a while, only really getting up for school and occasionally a hike. More recently though, I've been working out a lot more. I do cardio, toning, and even yoga 5-6 days a week (need that rest day). And now, I'm almost 12 days late 😩. It wouldn't freak me out as much if it was only a few days, but it's almost two weeks now. Any words of reassurance?

EDIT 11/27/17

Still have yet to get my period 😔. I've eased off my work outs and still nothing. Seems as though I've completely skipped it by this point. If I end up missing my next one, I'm planning to go see my doctor.