1st ultrasound Yolk sac is low

I had a little bit of brownish spotting this morning. I was supposed to have my 1st ultrasound on Monday, but doc told me to come in today. They found fetal pole and yolk sac, but it’s low in uterus. No heartbeat found yet. I’m 7w+2. They said that it’s likely a miscarriage, but to come back Monday to get another ultrasound. I also have to prep for a D&C later that day if they don’t find a heartbeat. Can three days really make a difference? Do you think there is any hope? I have my little girl by C-section so maybe this little one is attaching to that scar. Any positive experiences appreciated.