You could have endo for a long time without even having pain except during your period. I didn't know I had it (and hadn't even heard of it) until having to have emergency laparoscopic surgery for a tubal pregnancy 6 yrs ago. A couple yrs ago I started having various abdominal pain that just kept getting worse. Thankfully I knew what it was, but finding a dr who believed me was almost impossible. Taking gluten, dairy and caffeine out of my diet helped a lot for a bit, but mine was so advanced that when I finally found a knowledgeable dr I had to have surgery within a couple of wks. I suggest researching all you can on your symptoms and read blogs of others with the same issues.
What made you go to the gyno if it was mild pain? just curious :)
It would help to know how old you are, when the pain started, if you are sexually active (does it hurt with sex), have you tried getting pregnant?, when does the pain start? How long does it last...