Are Cramping, Spotting And Sore Breasts Post Having Sex Signs Of Pregnancy?

Hi, my question is .... is there a possibility i may be pregnant? the first day of my last period was feb. 9th 2015 . I did have sex within the week of my ovulation day . Im not exactly sure when my ovulation day would have been ... But i had sex on Feb 17th 19th and 20th and the 24th . I looked it up and it said my next period should show up around March 9th . Its the 3rd today Making my im guessing 8 - 10 dpo . My breats have been sore since a couple days after sex (i thought that was odd) they usually hurt the a couple days before my period starts. Then today i woke up to cramping and Spotting ( Brownish color only when i wipe ) . I took a pregnancy test and it was negative . ? Im Very confused at this point .