Week 6 pregnancy

Is it normal not to hear any heartbeat week 6 of pregnancy. Also, gynae told me not to have high hopes because gestational sac and yolk sac is smaller than expected and not really a good sign. Will see me in 10 days to see if baby progressing. (Seeking another gynae in 10 days time because first gynae was too harsh for my liking) should I be worry? What are the chances of miscarriage?