Anyone on the Trinessa birth control? I have been on it since my first period after my son was born and I've had periods…

Anyone on the Trinessa birth control? I have been on it since my first period after my son was born and I've had periods every month at different times during the month, but usually before the inactive pills, but this month I'm about to start the inactive pills tomorrow and still haven't started my period? Should I be concerned or does anyone else have this problem? I never had irregular periods before I had my son..