You have two problems that might interfere with conception. First of all, there are reasons to believe (as suggested by your doctor) that you have endometriosis. Second, if you're having irregular periods, then you're having irregular ovulations.
Endometriosis is endometrial-like (lining of the uterus) tissue in abnormal locations, such as on or in the pelvic organs. Because this tissue is menstrual in nature it causes inflammation of the pelvic tissues, resulting in inflammatory interference with conception, as well as mechanical blockage of the reproductive tract.
Endometriosis must be diagnosed surgically; it cannot be diagnosed just with an exam. If your doctor feels that you may have endometriosis, he or she is likely to have already proposed a laparoscopy to find out for sure. A laparoscopy involves placing a lighted scope through the navel to look into the pelvis. The outpatient procedure is conducted under general anesthetic. The sooner you receive your diagnosis, the better for your future fertility. And your doctor has good reason to suspect endometriosis: 70 percent of young women with symptoms suggestive of endometriosis have it.
If the diagnosis is confirmed, there are treatments available to increase your chances of conceiving when you're ready.
On the other hand, if your period problems are a result of irregular ovulation, not endometriosis, then your doctor can prescribe hormone treatments.