I am assuming the hysterectomy was for pain related to endometriosis, done through an abdominal incision. The 'lap' was a laparoscopy to look for adhesions or other causes of your pain. The cystoscopy was because you were also having urinary frequency. THe diagnosis of Interstitial Cystitis is probably entertained.
If all of these above studies were negative, then it is quite possible that your pain may be musculoskeletal in nature. That is, the pelvic floor muscles can sometimes become tense after years of pain related to endometriosis, such that they develop trigger points, leading to pain, pain with intercourse, and urinary frequency. You should consider asking for a referral to a QUALIFIED pelvic floor physical therapist, who can evaluate your pelvic floor and abdominal/back muscles for treatable trigger point pain.
PLease be sure that the therapist is a specialist in the pelvic floor, not someone who will just give you Kegel exercises. Please visit: http://pelvicrehab.com/ and
http://www.womenshealthapta.org/plp/index.cfm for more infor information on female pelvic floor physical therapy.