God vienna, this is always a tough one isn't it.
Sore boobs and stomach and back pains can be a sign of both, so I think theres no real way of knowing is there?
You know how I suspected I was pregnant?
Around a couple of days before im due I always get really bloated to the fact where im always uncomfortable, what made me think I was pregnant was the fact that I wasnt bloated at all and I felt really comfortable!! Even before the night I was due,
and sure enough I took a test the day I was due and it was positive!!!! :p