This right here proves how terrible sex education is for our youth! If schools taught a more comprehensive sexual health class we wouldn't end up with so many young parents who didn't know what they were doing. I heard an "old wives tale" that teenagers actually believe that they won't get pregnant if the girls on top or my favorite, that pulling out prior to ejaculation prevents pregnancy! These are not true. Pre ejaculation is fertile and can cause pregnancy. However, you do have to have penetration to cause pregnancy. As long as you were only on the outside of her genitalia you two will be fine. Please talk to a trusted adult about sex and practicing sex safely prior to acting. Even if its just your school counselor, and ask questions! There's nothing wrong with being curious, but it's best to get as much information as you can do that you'll be safe.
No you can not get her pregnant just from rubbing together. You would have to penetrate. And stress will cause for her period to be late.. you both with be fine.. if your really worried get a pregnancy test.