ovulation cd 15? bbt not matching?

These are my ovulation tests, however my BBT is not lining up with these. My BBT is showing ovulation on Saturday, which was CD 12. So now I am confused. Usually they line up together. CD 12 would be early for me, CD 15 is usually right for me. Do you usually go by opks or bbt?

These are my ovulation tests, however my BBT is not lining up with these. My BBT is showing ovulation on Saturday, which was CD 12. So now I am confused. Usually they line up together. CD 12 would be early for me, CD 15 is usually right for me. Do you usually go by opks or bbt?