7 weeks scan still no sight of baby

Just had abdominal scan, the sac is there. But inside it is totally empty. Nothing. Could it be that I had the scan done too soon? Or that the baby is still too small to be seen? I have 3 kids all with normal delivery. I got pregnant again last year, ended up miscarriage. This is my fifth pregnancy. Could it be that I’m going to have miscarriage again? 😢