Worried.. Advice!

Good morning ladies. I went today for my first official prenatal appointment. I thought based off my last period I was about 8 weeks and 5 days but according to my ultrasound I am only 6 weeks and 2 days. What's frightening is that we didn't hear or see a heartbeat yet AND my doctor is concerned about the color/lightness of my uterus. I go back in a week to check to see if we find a heartbeat, my hormones rise and if my uterus color looks the same. HELP!!! Has anyone else ran into this same problem? I need advice! I'm scared of another miscarriage!! 😪