Well, I haven't personally, but a close friend of mine got pregnant while on the pill AND using condoms. A friend's mom experienced a similar double-protection oops. So, it does happen, but it isn't common if you're being careful.
I would be more inclined to look back over the past month and see if you experienced any unusual stress (it doesn't take much!) that may have delayed your ovulation. Illness/injury, moving, more going on at work, etc. can all delay ovulation. It isn't unusual, either, even in women with very consistent cycles, to have an "off" month.
If you are pregnant, then a test should be accurate by now. GL!