I had sex about a week ago, and I was expecting my period on the sixth and it still hasn't come (although sometimes it does come later).. I took a pregnancy test which came back negative. But, I am still slightly paranoid. My breasts have been tender and I have been rather moody and feeling a little blah lately, although I am rather busy. I should also add that I have been working out at least 3 times a week (I am a competitive swimmer) and spend some time at the gym on the off days, usually doing cardio.