Is it my own heartbeat I'm hearing?

I convinced myself I wouldn't buy a fetal doppler to keep my anxiety down but after hitting the mark of where we lost our first baby (and my next ultrasound weeks away) I needed reassurance that the baby was doing okay.

Well, I bought one anyways 😂

I've been hearing what I was sure was baby's heartbeat right above my pubic bone on the right. I can hear the whooshing sound of my placenta and then I can find the steady beating of what I assumed was baby's heartbeat. It sounds like a choo choo train. I put the doppler to my own heart and it sounds completely different but...

I realized it's probably possible to hear my own heart rate and blood pumping through the placenta.

I know I'm being silly but is it most likely baby I'm hearing? How do you differentiate?