Iris,
Don't worry, let me share my experience, when I had my 2nd child, according to my period, It should be around 8 weeks when I saw the doctor, but after u/s scan, the doctor said may be only 5-6 weeks and also 只照到胎long and also no heart beat, and he asked me to follow up after 10 days and reminded me don't tell to my family first, at that time, I was very very down and think may have some problem on my baby, fortunately when I went to follow up and the doctor can see the heart beat and he said everything is alright.
Don't worry, hope you will get good news in your next follow up :wink: