Can't find heartbeat on home Doppler..

I know it can be very hard to find a baby's heart beat on your home Doppler sometimes but I am 9w1d today and still can't find it and it's making me worried/frustrated because I see all these girls post things online about finding it by 8 weeks. I am a very little person so I figured I would find it by now! I shouldn't have bought one.. I'm already a ball of stress worrying something will go wrong. Anyone have experience with these??