first time mummy!

In 6 weeks and 4 days pregnant 
And I don't feel pregnant in the slightest!! 
I'm scared for the nurse to turn round to tell me when I got for a scan there is no heartbeat or baby in there??! Why do I feel like this?? 
I don't have no symtoms apart from I'm always eating...is it even possible to take 5 test including a doctors test and not be pregnant or am I just being silly? Someone please help just to ease my mind