I think you O'd on cd16 last month with an LP11.
The month you were successful I think it was cd16 as well.
I think you have a slow rise. All the other signs point to an earlier O. open cervix, Ewcm, etc. I think ff puts too much emphasis on temps.
For instance this month it would've had me down for O 3 days later than I know I did. That would have given me a +ve at 8dpo, before my triphasic temps, which is just not possible.