thank you so much neli and Shasta!
It could be that you are off on dates. He/she may just be to small to see. I went in at what I knew was 8 weeks and they couldn't see the baby. I was freaking out. Now I am 24 weeks. My babies have always measured small that early. It could be something that simple for you. Fingers crossed.
Its might just b to early like ur doc said...when i went in i was supposely 7 goin 8 wks according to my last period so u might think ur 6wks but u might b less then dat...dont stress i know its hard ive been goin to by stress moments lately...just try n stay positive if the docs dont seem alarm u shouldnt either they go thru this alot they know its probably coz its to soon so try n relax...