Can unprotected "" a few days before periods lead to pregnancy?

on friday the 11th march, my gf and i played around a bit and we were rubbing genitalias standing up. i felt ejaculation coming so i pulled out quickly, but i also felt as if i got a like a drop on her labia. there was no . she says she had her last periods like a month ago already and her periods for march were suposed to come soon. but shes late by a few days now...she also had many many midterms to cram in the past 2-3 weeks. she says shes been cramping a bit, but no periods still... we are freaking out! is she even pregnant or is it just the stress?