Hmmm to me, this is only my advice/opinion/thoughts
That you had an anovulatory cycle and just now ovulating. I had the neg tests, cramps, headaches, I get tired when I ovulate and then I ovulate and Im fine. Maybe get some OPKs and see?? I know when I got pregnant with my 6th son they said I conceived him 4 weeks after my lmp, i said impossible, they said, it coudl of been late ovulation, which could be like yourself??