I too took a test too eary (first response) and had a faint positive on Wednesday, went straight to the Fertility Clinic and there was HGC but only 8.9 (very low) the nurses didn't seem to be very positive because it think they thought it was residual from my mc on May 14.
I had another blood test today and it is HGC going up, so definately pregnant but still so early it's difficult to say whether it will be viable.
I thought any line in the +ve area meant pregnancy it's just problematic testing so soon because so much can happen before your period is due.
I really hope for you that it is BFP and a sticky baby!