ob couldnt hear heartbeat on doppler

i had my second ob appointment today (16 weeks 1 day). when the doctor tried to hear the heartbeat with the doppler, she said she could hear movement but couldnt hear heartbeat very well. she seemed to get nervous and brought a bedside ultrasound. my husband was getting scared and asked why we couldnt hear it. she said something like “well shes very thin…the uterus is small and baby is small”. she immediately showed baby moving and pointed it out, but still couldnt get heartbeat at first. she said “if baby would just stay in one spot…” and then got the heart beat, but it sounded very muffled. she pointed at something and said i have an anterior placenta and to keep that in mind if i try an at home doppler. she still seemed nervous and frazzled until she left. my anxiety is out of the world that something is wrong, with my first baby they were able to hear heartbeat right away every time. is any of this anything to be concerned about or is it just my anxiety?

edit: thanks everyone! i feel much better, i think my anxiety over my last pregnancy ending in miscarriage and the few minutes of intense stress trying to find the heartbeat was making me overthink everything