Help me ?!?!

RyAnn

My period is due to come 8/18 but today 8/14 i start bleeding but its very light. For the past 2 weeks i have had sore breast, nauseous, constipation , heavy mood swings. I really did think i was pregnant but then the bleeding started. I have taken pregnancy test and they are negative but my ovulation test reads high. I am very confused can anyone share some insight