Can’t find heartbeat 😓


So I got my Doppler yesterday and used it for the first time. I was able to find the baby’s heartbeat twice! I’m 9 weeks and 4 days today. I just tried it again but could not find the heartbeat, even though I checked the same spot where I found it yesterday. I’m trying not to panic but We had a missed miscarriage at 9 weeks 4 days in July, so I can’t help but be scared that it’s happened again. Is it normal to be a able to find the heartbeat one day, but then struggle to find it the next?