I have read your question,
Since you have not mentioned your menstrual history it is difficult to answer your question . it not safe if the day was between 10th or 17th day of your period otherwise it is safe for you .
You missed a day on birth-control pill , and on the same day you have participated in sex there is a chance for you to get pregnant in this case.,
Hence I suggest you to undergo a pregnancy
test if you missed your period.
Wishing you a good health,