REALLY confused...

Jennifer • 41, Mom of 1, trying for Rainbow Baby.
So I posted yesterday that I was 4 dpo and having eggwhite cm tinged brown/light pink and cramping slightly. Went back to my calendar- turns out I was off on my days- actually 8 dpo. However, I took another OPK this morning, and it says today is my peak day (I took one yesterday and it was negative). Is this possible? Anyone else ever have this?