Later and later...

My periods have always been regular--28 day cycles, 5 days of bleeding. But for the past 6 months or so, my periods have been getting further and further apart. First it was just 3 days late, then 8, and now it is 12 days late. I called and got an appointment with the gyno about it--but of course they can't get me in right away (typical) so I am just wondering if anyone else on here has experienced this?