It presents differently in individuals from my experience. I personally have not had heavy or extended bleeding, but very painful cramping duirng and sometimes for the day or so after my period (only with urination though). Before I had a lap, I had extreme pain, extremely painful bowel motions and when I wee'd, ovary pain (mainly left where an endometrioma existed). Also had diharoea at times, or constipation at times, fevers, extreme lower back pain, shoulder pain (right shoulder which indicates a abdominal issue) and pain down my thighs. Sometimes my cramping felt like (I imagine) contractions would, in that it came and went in regular waves.
I also once had what doctors determined to be a case of gallstones, however, further investigation said it wasn't. After the discovery of endo, gyno said it was likely a bad endo flare up.