How not to worry??

I'm 12 weeks now with my first baby and waiting two more weeks for my next appt. Anyone have any tips on ways to not worry/stress about baby in between appointments? I bought a fetal heart monitor app, but think I'm too early to use, or it's just crap as it doesn't even hear my own heartbeat very well. I'm freaking out that something has happened and I don't even know it!