Guidance Please!

This cycle has been kinda screwy I think because I started Geritol. My temps usually correlate with OPKs, but not this time. I usually OV between CD 12/13 but didn't get a +OPK till 15. It's been positive for 2 days now (not so abnormal). Anyway, my chart shows my typical dip and rise, however 2 days prior to what the OPK has predicted. This has got me really confused. Now I'm not sure what to go by, especially since OPKs are still + today. Which method is more reliable? Has anyone else experienced this? Help please! Attached is my chart showing the dip and rise, however +OPK was yesterday???????