Can coming off bc mid pack cause you to skip ovulation and/or miss a period?

Elizabeth
I stopped bc on cd 8, got a period or something about 6 days later and it lasted about 4 days - if I had counted that first day of bleeding as cd 1, I'm on cd 24 now and no sign of period. I tested negative on cd 20. Could I still be pregnant? Or is it usual to have a late period after going off bc mid pack or at all?