Silent miscarriage, positive tests?

I'm supposed to be 8w3d but I had my first ultrasound today and only measured 5w5d with a fetal pole and yolk sac but no heartbeat. I'm fairly positive of my ovulation day plus or minus a few days. This means the embryo stopped growing three weeks ago. I have a follow up ultrasound next week but obviously it's not looking good. I took another digital test today when I got home and I'm still getting a positive 3+ week result. Would I still be getting positive tests if I miscarried 3 weeks ago? Thanks for any input.