I'd never suggest using a doppler, even when you get to around 16 weeks - before that anyone is unlikely to find it, least of all us who are completely inexperienced in listening to the different sounds (baby's heart, your heart, blood flowing through the placenta). Hell, my consultant couldn't find baby's heartbeat when I was 14 weeks and had to do an ultrasound instead! I asked her opinion on dopplers and she was very scathing about them - they can make you worry unnecessarily and they can falsely reassure you if you don't know what you're listening to.
Please please don't worry that you can't hear baby's heartbeat at 9 weeks, it's really early and a midwife wouldn't even try. Others may have really found the heartbeat that early or they may have thought they've found the heartbeat that early, it's difficult to know without proper confirmation from a fully trained professional.