it is possible. take a HPT asap!!
how late are you? try a pregnancy test with first morning urine ie some you have held in for at least 4 hours. doctors dont really like to test you until you are about 7-10 days late for your period x
If you've had unprotected sex, you could be pregnant, but your period could be late for other reasons (stress, illness, hormonal fluctuations, etc). The way to know is to take a home pregnancy test using first morning urine. Good luck!