So my period was due on the 15th however I am now 4 days late my period is always regular it always comes on time but also for the pass week or so my breast have been sore I guess I can say like my left boob hurts more than my right one and I don't know what to think about it I took a test the day my period was suppose to come and it came out negative so I don't know what to think  .... Any ideas? Has anyone had this happen to them before and still ended up pregnant?