If you had unprotected sex then there is a chance that you are pregnant. Some women ovulate during their period time, which increases the chances of getting pregnant. By knowing your ovulation dates, you are able to determine whether you are pregnant or not.
When it comes to unprotected sex it's open season for STDs, aids & pregnancy. Everyone is different, I've read articles about women that had "bleeding" up until their ninth month. Condoms & birth control used together will give yourself some safety