is it possible that my fiance is pregnant?

okay so me and my gf have been sexually active for a few years now. we have only had intercourse a few times and its been months now since we last have. but we still mess around quite a bit..usually around 2-3 times a week. i never penetrate her because she is not on any form of birth control and we dont use condoms. i never knew about "precum" before until just recently and heard that it could cause a pregnancy and now we think shes a few days late on her period. although she has an irregular period and sometimes it comes early other times it comes late. is it possible that she is pregnant fromt this? thanks a bunch