Gestational sac but Can't see baby should be 11 weeks but looks like I'm only 5.

I went to my 1st appt. Yesterday. I should be 11 weeks today. She did ultrasound and could only see gestational sac. She said it looks like only a 5 week pregnancy. But I took pregnancy test exactly 5 weeks ago. She said she doesnt know if there is a baby or not. My heart is just aching right now... I know there is still a chance of baby being ok and its just still too small to see yet but has anyone else had anything positive come from something like this or do you know someone that this happened to and their baby was ok? I just really don't know what to do. There is nothing I can do but I need hope and faith that everything is fine...