Help! Miscarriage question!

Laur

So the last 3 days I have had light - medium brown spotting. Thought I was 5w5d but I went for an ultrasound today and it read 6w1d. They saw a yolk sac & gestational sac, and everything seemed great. However, they didn’t see a heartbeat. Doctor thinks it’s the start of a miscarriage.

What do you think? Is it still to early to tell?