Did you take your temps late on the 15th & 17th? My initial reaction is that cd18 looks more accurate, especially with the open circles on your other "high" temps. Your coverline looks too low to me. I think your coverline should be closer to 97.1 with an o date of cd18. JMHO. You've definitely o'd though.
If ff is correct, then it looks like you're going triphasic!