Genital Rubbing, No Penetration, Possible Precum

Hi, my girlfriend and I were fooling around last Saturday on the 28th. We were playing around and were rubbing our genitals together where I rubbed my penis around the opening of her vagina. I didn't penetrate her however there was some rubbing and I wiped the precum off the few times before rubbing it again. This lasted only for about a few mintues. However today would be considered day 30 in her cycle where she was supposed to get her period. There is no news of her period yet and I'm getting a little freaked out. She got her period on day 29 last month. Is there a possible chance that she can get pregnant from what we did? and also is it normal for the period to be somewhat off? *I didn't penetrate *I didn't ejaculate at all *There was a little precum Am I freaking out for no reason? Can she get pregnant from precum? She doesn't know that I'm freaking out about this issue as we didn't talk about this at all.