Scared & Don't know what to think😢

Hello ladys im so concerned maybe someone has been in my shoes and seen the light at the end of the tunnel..... Well ii guess ill start by telling y'all when my last period was and go from there... My last period was on July 3rd and based on that ii should have been 8 weeks today... Well ii had my first ultrasound and my sac is only measuring at 6 weeks there's is no sign of a fetus in the sac 😢 doctor said for me not to lose faith tho that ii had a perfect round sac & maybe I'm not as far as ii think ii am he did say the only thing is that ii have a tilted uterus & that can be the reason we didn't see anything... he had scheduled my appointment for 2 weeks from today to do a rescann but a couple of hours later ii got a call that another doctor had reviewed my ultrasound and they wanted to see me sooner (next friday) at a diffrent clinic.... has anyone ever been through this and had a baby and a heartbeat 1 week and 4days later...im trying not to stress to stay positive but its so hard😭😭 Someone please give me some hope....