Been TTC for months, period is over a week late, took a pregnancy test the other day but it was neg. Then yesterday thought i was starting my period but it was super light and a bit muscusy and very dark in color, not bright red like normal. Also came with cramping, but not the same as my usual cramps. Now today there is no signs of blood, could this have been implantation bleeding? Also, note my breasts have been extremely heavy and sore the past few days too.