I've been told by a GYN that even a light period is still a period. However, I've also talked to Mom's who had light periods all through their pregnancies.
The fact is that anytime you are having sex, you risk pregnancy.
The only real for sure bc is abstinence.
To find out for sure if you're pregnant or not, take a pregnancy test.
You can get a FREE and CONFIDENTIAL test at a pregnancy center, look one up near you: