The girl is on her period, she's not pregnant.
There is so much misinformation here, and the standard of sexual health education is clearly poor.
Unless the man properly ejaculates the risk of pregnancy is miniscule. Implantation bleeding can give light spotting, but nothing you would mistake as a period. Some studies have found pulling out (and therefore regular exposure to pre-ejaculate) to be more effective than condoms!
Obviously not STI protection and pulling out only works if done with 100% accuracy and that's not always easy to achieve.
100% impossible for the OP to be pregnant. Everyone else - stop worrying the girl.