BBT chart question

Ashley ā€¢ Been with my husband 12 years, but married Aug. 2015 :: we have two daughters šŸ’—šŸ’— :: TTC #3
Do I go by my dip when I ovulated or by what glow put on my chart? I had a positive OPK on CD15 and CD16? This charting and OPK's is confusing to me!Ā