I'm a med student as well...
Not to be mean, but you should know this.
A very small amout of sperm live in pre-ejaculate, but if you were both clothed, you have nothing to worry about...sperm can't travel through a condom, let alone 3 layers of clothing.
Good luck with med school.
there is no way that it should be a concern, she can not get pregnant though clothing, you all will be fine , no kiddos just yet, means no worries LOL jk ...you and her are both fine and will have free lives till you have intercourse..
you were both clothed? there is no way that she could get pregnant. her periods can be irregular because of a change of diet or stress or anything, but you could not have gotten her pregnant. there are not many sperm in pre-ejaculation fluid, but they cannot pass that kind of distance--it would somehow have to get directly into her vagina and even there the chances are slim. but in this case you couldn't have gotten her pregnant.