Wondering

I had an ultrasound today at 6w1d but they weren't able to see baby or yolk yet, just a sac. The ultrasound dated my pregnancy at 5w3d. They drew my blood and it was 13592 and my progesterone was at 15. When I had my blood drawn in Tuesday it was 6384 so it more then doubled since then. The dr said she thinks it's about 50-50 for a miscarriage or not having a miscarriage. She said my numbers look pretty good and maybe i conceived a few days later then I thought. I go back monday for another blood draw and ultrasound on Tuesday. Has anyone had an experience like this? After a previous miscarriage I'm trying to stay hopeful but very worried!