Bbt chart gone mad...help!

Melissa • Mother of 1 two year old 🌈 and 4 👼🏻 🌈 #2 due 12/23/19
First, not sure why these are all showing that I temp at inconsistent times... All were around the same time except cd1.. I think ff assumed that was the time I always chart....
Anyways... What is going on here? Positive opk cd18.  Temp spike cd20 (although not huge) then this huge dip 5dpo?! I almost always o between cd18 and 20...I have ewcm  yesterday and today but negative opks since cd18.  So confused  😞