Renstar - I found some research for you. I've rewritten it as it was a bit long. Basically:

In a study done on 240 non pregnant women many were found to have HCG levels of under 5. One case had a level of 4.6 some had 2.5 but most were under 2.

It then went on to say that only levels over 5 are considered pregnant as it is very possible to have lower readings of HCG but not be pregnant in the latter part of your cycle.

As you head towards menapause (peri-menapause) you can have readings over 5 and not be pregnant.

I also found a site that was all about comparing pregnancy tests. It said not to use anything more sensitive than 20miU as the more sensitive tests can detect this naturally occuring low levels of HCG that may be present in a non pregnant woman. You just may be one of these women that have it occuring in you.

I once had a reading of 3 after having had 3 different brands test positive (including a digital one) and was told I had probably had an early m/c (was bleeding lightly at the time). My gyno told me that there's no way that you can have a false positive from 3 different brands so I would have been pregnant for sure.

You might be better off to use less sensitive tests and only test when AF is overdue, it would save you a lot of worry. I'd also suggest you start to chart so you know exactly when you O then you will know when AF is due, and if you go over you should test.

I've also read a lot about false positives with that brand you used so if I were you I'd be getting more reliable tests for the future. The LC ones are great and I've never had a false positive on them. I used them for the last pregnancy and this one and they were very accurate. I used them on several cycles where I wasn't pregnant and I never got a second line. When pregnant I got a faint line then a darker line the next day, off to the doc and tested positive straight away both times.

Good luck.