Can menstruation cause diverticula (not infected) in colon to cause some pain/pressure/discomfort in pelvis? us of pelvis fine.

No: There is no association between menstruation and diverticula. You're very young even to have diverticula. Was this seen on a colonoscopy? You can have endometriosis within your pelvis (including on your colon) which can feel worse around the time of menstruation. Treatments for endometriosis include Depot-Lupron, surgery, continuous BCPs, daily Letrozole. Endometriosis is hard to see by sonogram