cmoflorida

I will start off saying that i had my regular af on april 21, which was 4 days long and all normal...the cramps the night before, then starting that morning heavy the first day, then lightening up the rest. Then my b/f and i were trying to concieve 4th-6th of may (while i was ovulating the most), and i had and still have the symptoms of early pregnancy for the past month or so but i have tested negative 4 times a hpt, i know that they can give a false negative, or just not work for some i did the calculations and if i am pg then i would be right around 7 weeks, now for my problem...yesturday around 4pm after intercourse i started to have a little bleeding it was a very light red color and very thin, then it stopped for about 2 hrs. then i got some mild cramps, then it came heavy, w/o stringy lining, or clots just more blood, this morning i woke up with cramps still but a little less harsh than yesturday, still bleeding but back to being thin and faint in color and i have no cramps at all this is really stumping me since i didn't have af last month and now this and i have always had the cramps the night before and that was it. Are my calculations wrong and am i just now getting that implantaion bleeding, or is it my period, or spotting? I just don't get it! Can anyone help me out with this???

p.s. This is not at all like my " normal" af, and i have been under no stress, not even about trying to concieve...I just don't get it.