Ugh please help :(

no one ever comments on my posts and its driving me nuts. Anyway, my period is 4 days late which is the most unusual thing considering i have an extremely regular cycle my periods are always spot on every month. Ive never been this late before the last time i was late was almost two years ago, but still wasnt this late. I took a test the day i was due- Negative. I took a test two nights ago- Negative. I took one this morning- Negative. I wasnt stressed or anything prior to the day i was due. Has anyone else had this?