Late BFP??

Liza • 👦🏻 5/5/16 👼 8/13/18 🌈 👶🏻 12/15/19 👧 12/4/2019 (our 🌈 baby came early) 🤰with baby number 3

Anyone ever got a BFP after a week or more after your missed period?? Currently 9 days late for my period and testing bfn! If you got a BFP late, what was the cause?