Well the two days of eggwhite CM after FF has marked your O as well as the fact that your cervix was still open after would make me think CD23. Hopefully some girls with more experience will chime in. Based solely on temps I would agree with FF.
What is your typical luteal phase length for past cycles? Looks like your last cycle was rather long so I doubt the dip is due to impending AF.
Either way your BD timing looks GREAT!
Keep us posted!