8 days late and a negative test

Hello all, so I'm 8 days late and I had some symptoms, I could swear I was pregnant and then my first response came negative yesterday. I had unprotected sex several.times with my boyfriend last month only using the pull out method. The funny thing is that I experienced some symptoms like: headache, bloating, heartburn, nausea, low back pain, my beast and specially the nipples were very sore. Now I think those symptoms are all created In my mind. But my period never gets that late. Do you think that is possible that I'm pregnant and get a negative test after 8 late days? Thank you