Hey Kirsty, I think I've heard that if your doc has the more advanced internal u/s equipment then you can hear the HB from quite early on. But if it's just with a doppler then it's unlikely that you'd hear it at 9wks. Apparently a lot of docs won't even try the doppler until around 14wks or more. You will be able to see the heart beating on u/s @ 9wks though.

Good luck!