Endometriosis?

Many years ago, I started BCP because of very painful and heavy periods, and spotting between periods. The doctor said it could be endometriosis, but to see if the BCP helps. It did for a long time but now, years later, similar issues are coming back, as well as very frequent nausea and cyclical bloating  (and I'm not pregnant). Could this be endo? I have a GYN appointment scheduled, but I know endometriosis can only be officially diagnosed through surgery and that scares me!!