I have endo as well, and it can be really horrific. Do you know if you ever skipped periods? It's normal to have 11-13 periods in a year. Anything deviating from that is probably irregular. Do you have any record of how long they lasted before you were on the birth control? Most people with endo that I've known (myself included) had abnormally long periods. So that may be something you address as well. I hope that this information helps! Best of luck with it. It's an awful disorder and it can really impact how you engage in life, so I hope that you get everything sorted out soon.