Im 12 days late and keep getting bfn. I have pain in my boobs and pressure in my lower abdomen. I…

Im 12 days late and keep getting bfn. I have pain in my boobs and pressure in my lower abdomen. I went to the OB yesterday because I've been having brown discharge. He say that it may have been a very light period. Problem is I don't know exactly when it started so I have no idea when I'm due to ovulate ☹️️oh the struggle of TTC