Hi thanks for your question.
Your having periodic excruciating pain lower abdomen and unable to conceive.
You’re all ultra sound
reports are normal.
Monitor your pain, if you feel pain 12 to 14 days after your periods, then it is pain due to ovulation and is called as Mittelschmerz
The other condition which gives you this periodic pain could be early stage endometriosis
not picked up by ultra sound and needs laparoscopic examination.
Hope I answered your question.