need answer pls help...

Yesterday I had my TVS ultrasound. My obgyne said on my 1st check up she said I am 7 weeks since my LMP was july 29. So yesterday I had my first ultrasound. My husband and I were suprised when the doctor said I was only 5 weeks erly pregnancy. Nd so worried when she said let wait and see if it will continue and i wiil go back after 2 weeks for my next follow up ultrasound. It says ecerything is normal. But ia am still worried right now... Is this serious? Is my baby ok? Or it stop growing.. Please hope to hear some answers.