I'm not a doctor but your symptoms do sound like they could be endometriosis. I would recommend a consultation with a gyn knowledgeable in endometriosis to rule out the possibility. The fact that you state your symptoms get worse during your period is really a red flag. Intermittent diarrhea and pain with bowel movements are classic signs of endo and would especially be suspect in a woman whose pain increses with her menses.
As for adhesions, they are always a possibility. Have you ever had abdominal/pelvic surgery? That would be one source of adhesions. If you do have endometriosis, then that in itself is another possible source of adhesions. Most, if not all, women with endo have adhesions to one degree or another. Pelvic inflammatory disease can also be a source of adhesions.
I definitely think you should get in to see a gyn.
I have endo and have been dealing with it for 17 years. Let me know if there is anything else I can to to help.
Good luck!
-- Debbie