Early pregnancy signs? Help.

Melissa
My breasts have been incredibly sore and firm for the past two days. I took a pregnancy test this morning and it came back negative.  I just recently had very light spotting but nothing more. Breast tenderness has never been a PMS symptom for me. Can breast soreness begin before a test can detect pregnancy hormones? My cycle is has been unpredictable for the past few months so I'm not sure when my missed period is or when to time a test.