12 days late

What's the latest you've ever been on a period? 12 days late, BFN when I tested 3 days ago. I have a 28-30 day cycle. I've never been this late before. I was on birth control, but got off the pill 6 months ago. Prior to being on birth control, I was still on a regular cycle. I'm not in any great amount of stress.... Going to make a doctor's appointment, but I'm just curious if anyone who's never been late has experienced this before.