very early pregnancy symptoms

Countdowntopregnancy.com lists 10 very early symptoms of pregnancy. I have 2 of them, that I normally don't have. Of course I want to read into this. My question is- how can you have symptoms before implantation has occurred? I know some of them are just related to your cycle- like increased progesterone levels relaxes muscles in your body, including the gut, leading to gas. I want to believe that these 2 new symptoms mean something but I just don't see how they could since I'm only 6 dpo.