Yes. I was charting for 8-9 months and would get a thermal shift. I never got a positive OPK. After about 10 months of TTC on our own, we got referred to a fertility specialist. He ran blood tests and did ultrasound scans and said I have PCOS and don't ovulate. I went on Clomid. 50mg did not work for me. Second cycle I took 100mg and I ovulated and had a 29 day cycle. The third cycle I took 100mg again and conceived. My fertility specialist said if you have PCOS temping isn't accurate.
Based on the fact that you've got two LOs, I would assume that you probably ovulate at least semi regularly. What are your cycles like?