Careful with the doppler, if you aren't trained in how to use it it can be really tricky, especially since you're only 9 weeks along. Don't freak out if you have a hard time finding the heartbeat!
I had a really hard time finding the HB on my dopper before 11-12w so it's different for everyone. If you'd be freaked out by not finding it on your own, don't use it yet. I loved having it though, especially before I started feeling movement and my appointments were 4w apart.