What Causes Delayed Periods And Sore Breast While UPT Is Negative?

yes I had my cycle on dec 27 i should have started on jan 24 def by the 25 and today still no period. i have sore breast off and on ( for sure larger) using it more and sleepy.i took a preg test on wed which was neg do you think it was too early ( i did not use first morning urine)