Can a positive OPK be incorrect?

Lisa • Married 5 years to a wonderful man. Son born 26 Jan 15. Expecting another boy in Nov 16 X
Hi Everyone
​This month my bbt and OPK suggest I ovulated on cd14 (same as last month) but I decided this month to have sex a few days after O too incase I was missing a trick
​Anyhow - today I'm supposedly 3DPO but I have loads of creamy CM (which had an odour - never had this before) and my cervix is super super soft. It was very soft yesterday too.
​Anyhow we had sex today as I'm worried I'm ovulating later than all the indicators suggest.
​Anyone experienced similar? Please help? Feeling frustrated...