I have really sore nipples, what could this mean?

Hi. I usually get really sore breasts right around the time I ovulate, but this month, no sore breasts. So I figured maybe I didn't ovulate this month or something. But yesterday my nipples, not my breasts, just my nipples became very sore. I am supposed to start my period either today or tomorrow. I have had a few twinges in my lower abdomen over the past few days as well. And while sitting in my class tonight I got a wave of nausea. I am wondering if maybe I am pregnant. I had a very light period on the 31st/1st(sometime in the night) which lasted barely 3 days when I usually have a heavy period fading into lighter around the 5th day until it stops on the 7th day. Just some stuff that has been plaguing me over the past 2 days. Maybe some insight?