Anytime you have sex - "protected" or not - you risk getting pregnant. That being said, you had a period on the 15th, so you really won't know if you're pregnant or not unless you miss the next one, which is like two weeks away.
You can get a FREE and CONFIDENTIAL test at a pregnancy center. Look up one near you at this site:
I also just want to encourage you to reconsider being sexually active until you are married. The consequences of your actions at this point are usually NOT going to be good ones.