Sweetie, relax, you are pregnant so enjoy the ride. I'm no expert but if they dont write quantitive HCG then they have a cut off limit for a positive if that makes any sense....if the level is really low then they wont count it as a +. Also, most of the tests you have just used are a sensitive nature....I think they are 20/25 min of HCG levels to pick up and as HCG levels double every 48-72 hours (2-3 days) then say you are just as 20 this week so 2-3 days ago you woulda been 10 and 2-3 days before that 5 and so at the time you did that blood test potentially your levels may have only been 2.5 or even less