I never ejaculated inside her but I'm worried

hello, my girlfriend and I engaged in sexual activity last month on the 24th. We were laying together and getting extremely close without clothes on. I was only inside her a couple times for less than 10 seconds each time, I believe I only made any motion once though. I never ejaculated inside her but I'm worried about precum and/or semen on the bed or on one of us possibly getting inside her from all the touching :( we're freaking out now and are NOT ready for a child. She missed her period that was due yesterday and says her boobs feel very sensitive and noticeably fuller and heavier. Her mother even noticed that they looked bigger. Normally before her period her breasts are never affected, but we are aware that it is a pre menstrual symptom. Just today she told me she feels herself bloating and that does normally happen before her period, but again, we're aware that this is an early pregnancy symptom. PLEASE HELP! Is she pregnant?