Anyone experience this?

I need some stories or insight.. I had an ultrasound done at 8 weeks and 6 days. Everything came back normal, and we heard the heart beat at 180 bpm. Yesterday, I went to my 12 week prenatal visit, my doctor said everything was fine, but when we went to hear the heart beat with a fetal Doppler he said he couldn’t hear it. My doctor said this is normal until about 15 weeks because the baby is still under the pelvic bone… I’ve had no bleeding, just a “normal” pregnancy… has this happened to anyone else?