Your doctor should have done a sono instead of sending you home worried. I also had the Doppler done on me around the same time and had the same thing happen. I'll be 18 works on Wednesday and baby is doing great. I wouldn't worry over it.
Well I seen the heartbeat in an ultrasound at 6 weeks 4 days but I never heard it with the doppler at 12 weeks 5 days so nervous
I also wanted to add that sometimes, health care professionals can't always pick up heartbeats with dopplers. With my first, we had heard previously heard the heartbeat by doppler near week 10 (early) but they couldn't find it week 14 (both my doctor and the resident). The ultrasound showed no problem. Do you think your medical provider would be open to giving you some pointers?
If this is a home doppler there is such a huge margin of error for them, also home dopplers are not made to pick up the heart beat until after 15 weeks. Even the medical grade dopplers can't always pick up the heartbeat until 15 weeks or later. I am 17 weeks and my doctor still can't get the heartbeat on doppler because of how active she is. Ultrasound is the only way to see and hear the heartbeat for me right now. Goodluck I hope you have a happy and healthy pregnancy.
By Doppler sometimes it can take longer. I was in the ER for nausea/vomiting at 13 weeks and couldn't hear it on Doppler. Ultrasound showed she was ok--it wasn't until I was 16 weeks could we finally hear it. Make sure you focus the Doppler really low on your pelvis, and don't be discouraged if you don't hear it yet.
You can usually hear a heartbeat by 7 weeks and definitely by 12 weeks. I had an emergency ultras sound at 10 weeks 1 day and we could not only hear a HB but his tiny arm buds were waving around. Maybe they got your conception date wrong? Good luck