What Causes Nausea And Intermittent Constipation?

I ve been having some nausea in the morning and throughout the day, my beasts have been really tender and sore, I ve been having food aversions and some small cravings, also my bowels haven t been working so I ve been constipated on and off..these show some symptoms of pregnancy I ve read and it s been a few weeks since the sexual intercourse, but I ve had a period, a late one albeit that only lasted 5 days when it usually lasts a week or more..could I be pregnant? I took a home pregnancy test too but it came back negative, this was taken two weeks after the intercourse..also I ve been bloated a little