Im i pregnant? please help..?

ok so my last af was dec.13,2010 and i took a clear blue on the 30th and got a happy face...so we bd on the 30th,1st,2nd and 3rd of jan. my af is due 15th of jan. im 13 dpo and when af is coming my will hart and lower back too, and really bad cramping..but i have none of that my nipals will hart when they rub up on somthing...and sleepy alot and headacks lots of them...i took a pregnancy test around 1:53pm and it gave me a ( - )so do you thank i could be pregnant? thank you guys for helping me out..