12 days late and negative tests

Has anybody ever seen or heard of this??!! My period has been like clock work and I've never been more that 3 days late. I took a test this morning and still negative! Somebody please, PLEASE tell me if you have ever had this happen! I did have weird brown spotting after my period last month that lasted for about a week so that was different and I've been feeling very "wet" down there. Like I've started but when I go to the bathroom there's nothing. Please help!