Even now I can lose babies heartbeat if I move Doppler even slightly, I wouldn't panic if you can't find heart beat. I couldn't with my firsts and got myself in a right state and she's nearly 8 years old now lol . If you are going to try again I suggest very low down and pointing almost underneath or right above pubic bone, moving Doppler very slowly and changing angle after a few seconds. I'm sure if you find it you will know it, it will sound much faster than yours . Good luck x