What Causes Late In Periods And Its Treatment ?

Hi. For the past few months I have had fairly regular cycles with a cycle length of 40-45 days. I am two weeks past my expected period this month and keep feeling like I am going to start but nothing.... I just noticed yesterday a teeny tiny bit of brownish mucus type discharge on the tissue when I wiped and once again today after I went to the bathroom. Nothing on my panty liner... just tiny bit on tissue. As of a few days ago, negative HPT. What do you think?