I sometimes get fuller breasts before my period. BUT it could be an early sign too
Mine get pretty big and sore, the nipples extremely sensitive, pregnancy soreness is pretty significant, covers most of the chest instead of certain spots. But nterrell is right, take a test if you dont start in a week.
I always get fuller breasts that hurt a lot about four days till my period. When I was pregnant, it didn't go away for a while. Wait for about a week, and if your period has not come & your breast are still full & sore then take a pregnancy test.