Ovulation pain but negative OPK test

I've been TTC 2 months now and know I have chocolate cysts to right ovary and endometriosis. I'm day 15 into my cycle and noticed on day 14 I was having abdominal cramps like a full bloated feeling to my right side, I'm assuming it's ovulation pain as this is around the time I should be ovulating but all OPK test are negative!!!