Can you miscarry and not know it?

I wouldn't worry quite yet. It's actually pretty common for the doppler to not pick up a heart beat. For some women it's really difficult. A lot of times a doctor will schedule an ultrasound to check the heart rate if the doppler doesn't work. It'll be much easier to find the heart beat in later months - 11 weeks is still pretty early. I got lucky and they found mine right away at 10 weeks. But before my appointment I watched some videos of women doing it on youtube and for some of them it took over twenty minutes for the nurse to find it. I know it's got to be scary not hearing it, but try to relax - a lot of women have been through the same scenario and their baby was fine. And if you still have you pregnancy symptoms - that most likely means everything is fine as well. If the doctor thought something was wrong - you'd know. Don't worry - it's just a little early for your little one yet.