Is Pregnancy Possible After Non-penetrative Sexual Activity?

Hi, Recently me and my girlfriend have messed around in bed, we just kept dry humping nude without protection and there was no ejaculation nor was there penetration only precum and wetness, also keep in mind we are both virgins. Here period was due on the day we messed around but its been 11 days and she still did not get it. Her period is usually irregular and doesnt come on time and she did a urine pregnancy test 4 days after her period was due and it showed negative. Now this can be a false negative so is there a possibility she can get pregnant what we did or should we not freak out?