Hi, I had same, weak positive 6 days after AF due then another weak positive a few days later. Went to GP who refused BHCG said I didn't need one. Was not happy at the time but glad now that I didn't. My dating scan showed that I was 6 days behind what I thought and I must have ovulated on day 20 and faint positive was only 11 days post conception, not surprised it was faint! If I had have had blood test I would have found same as you and been in a blind panic!

Try not worry and wait for scan, even if they can't see hb they should be able to measure and give you dates. it is a worrying time, I have never been so anxious in my life! Sure it will all work out fine. I have to keep telling myself to trust my body, it's not easy though!