Hard to find baby? 12 weeks

So Monday I had an OB appointment I was 12W2D, anywho when the doctor came to check the heartbeat it took them awhile to find it. The nurse had to press really hard and eventually after a few minutes found something (HB was 160) . I don’t know my anxiety is telling me that wasn’t the baby and was my placenta instead. I’m sure they know the difference but it’s just kinda scary because I don’t feel any movement or anything. Anyone went to an appointment and baby’s heartbeat was hard to find around 12 weeks?