Does Sore/tender Breasts And Light Vaginal Bleeding Indicate Pregnancy?

I am wondering if I am pregnant, I have had extremely sore/tender breasts for about the past week. I am due to have my period within the next few days, though I do not have very regular cycles. I have never before experienced sore breasts with PMS. This morning I began with very light/spotty bleeding when normally I begin my period with very heavy bleeding.