Silent miscarriage

I had an US yesterday, I was 9w1d. But I was only measuring 6w4d and they couldn’t find a heartbeat. The US tech said maybe I ovulated later (but I think that is highly unlikely as I’ve been tracking my cycles for 18m and never ovulated late). My Dr wants me to get another US in a week just to be sure. I’ve not had any bleeding or severe cramping. I’m feeling pretty hopeless, this is going to be the longest week of my life. Has this happened to anyone else before? Is there any point on holding on to hope that my baby could be still alive?