Can she get pregnant?

Whoa, pardner!! Even if your gf is pregnant (which I seriously doubt) she would not be showing symptoms yet. Especially not the tummy - thing. Pregnancies don't start to show til you are about 5 months pregnant. That is when the uterus rises up to the belly button. First, try a home pregnancy test. If that is negative, but her period still doesn't start, find an obstetrician/gynecologist who is willing to see you for a free consultation.(or at least cheap). And if you all escape this unscathed, go together for some birth control. Good luck!!!