Possible miscarriage

I found out yesterday that my baby is only measuring a little more then 6 weeks and should be around 8. The dr thought she saw the fetal poles and a slow heartbeat. It’s possible that I ovulated late and I’m just not as far along as I thought, however the dr did not sound very hopeful as I’m pretty regular. I took a test Saturday and it tested positive right away. I mean, 10 seconds and the pregnancy line was darker then the other one. Also, I neglected to tell my dr that I have a tilted uterus. Does anyone know if that makes it harder to see during the ultrasound? Trying to hold on to hope where I can, but also want to be realistic about my situation.