happycow

Hi, I'm 24 and my Girl Friend is 28, its been 14 days since we last had sex and her period was suppose to begin about 5 days ago. When we did have relations, we used condoms and plus I pulled out before climaxing. We did do other thing which might have caused semen to maybe drip down there, but if it did happen, we are both totally unaware that it did. Her period has never been late, and usually a week before her period she has breakouts and some mild cramping. She had a feeling her period wasn't coming because she did not have these symptoms before hand. Then 4 days gone by, and she started to have very light bleeding in which she only sees when she wipes. Today is day two of this light bleeding, and she planed on visiting her Doctor for a pregnancy blood test. She however changed her mind and canceled the appointment, telling me that her period has got heaver. I don't necessarily believe that this means she's fine but she won't listen to me.
I read that stress can cause a situation like this. However she hasn't really faced any new stresses, besides her usually stresses at work (which is normal for her). The only time she was really stressed was when her period was late.. She is not on any medication and she has not had any weight changes or anything like that. Does this sound like she is pregnant or is this just an unusual period?