Dopplers and paranoia....

Hi all! So today I am 10 weeks with twins. I last saw them at 8 weeks 3 days and everything looked great. I have been trying my very best not to get too worked up over losing a twin, and so far I have done a good job of that. I decided I would get out my fetal doppler from my first pregnancy around 9 weeks to see if I could pick anything up. So far, even just now, I can only seem to find one heartbeat! And it is always in the same spot.... Pretty sure that is baby A. Baby B has kind of been stubborn from the start as far as being tucked back and getting good traces on early abdominal scan. Soooo I am just praying that baby B is just harder to find and nothing terrible has happened. My question I guess is have any other twin mommies had a hard time finding both beats with a doppler?? Long post for a short question, but thanks in advance for any answers. :)