Hi! i have a concern, i am almost 6 weeks pregnent as per my last periods and today i had an ultrasound...i was able to see a sac of 15mm but it was empty as there was no fetus..Dr asked me to come after 2 weeks for another ultrasound...now i am stressed as Dr said we must have seen fetus today (i have no health issues, absolutely fine) i am too stressed, please suggest me something or tell me why i didnt see my baby today??