Is it just me?

I had bleeding (light brown) at 6 weeks and had a scan everything was fine an embryo was present, as well as a sac and a heart beat, they said everything was fine. Since then i have a constant worry in the back of my mind that im not pregnant, i know i am due to loads of morning sickness, on and off sore boobs and tiredness also since bleeding i have done like 6 test (4 digital) and all positive, so why am i constantly feeling anxious