Heart beat 178 ultrasound but nothing on doppler

Hi. So is it just too early? I'm 10 weeks 4 days. We got to see a strong heartbeat on our 8 week ultrasound but when I asked my Dr if we could hear it on the doppler today he wasn't able to find it. I'm a bit nervous :( ... I hate the first trimester because it's full of people saying ... you're too early. You're not far along etc and it feels almost as if your pregnancy isn't validated until you're at least 20 + weeks. So frustrating