tell me im crazy and it's normal.

Ok so I'm 11 weeks today and I listen to baby's heartbeat every other day on a fetal doppler. I heard it yesterday and somehow just tried listening in today instead of waiting for tomorrow. Well I didn't hear baby at all and I tried 3 separate times today so now I'm extremely worried. Has this happened to anyone? Is this normal to hear it somedays and somedays not? 😏😞