Don't worry. When the first time I went to see the doctor, according to the period, I assummed I've been pregnant for about 8 weeks, however the doctor said there was still no heart beat of the baby and he asked me to come back 10 days later and fortunately my baby was having heart beat and the doctor said the baby was only 8 weeks, so the first time I went to see the doctor, the baby was around 6.5 weeks and now I am pregnant for 33weeks. So Don't worry, I hope you can see the baby's heart beat next week.
Good luck.