Advice please...

Iv been to the hospital today I'm 6 weeks,  to get an early scan due to having a miscarriage at 15 weeks last time round. They said was no sac or anything. But that my mucus and fluid had definately thicken. They did a normal and vaginal scan both couldn't find nothing. So worried they said not to yet as I could be earlier than we thought. They took my bloods and said they will tell if my levels are rising. All my pregnancy tests say positive. Did one when i got back and it's positive still but faint. Please someone help.....