battery - yes, I do use CBFM. The girls over on the CBFM thread are lovely an dv knowledgable.
Usually in the first month, you can get readings that may suprise you but after a couple of months it settles down and you normally get a few high days followed by 2 peak days followed by 1 high day.
Where the CBFM is clever is that it measures the 2 different hormone levels.
As for you query about the lines on the stick for the CBFM, I've c&p an explanation from KnackeredCow on the CBFM thread which I don't think I can beat!:
The one nearest to the end you pee on is LH. This becomes darker as LH surges. LH surges approximately 12 - 48 hours before you ovulate.
The one furthest away from the end that you pee on is oestrogen. The technology of the stick uses a negative assay and this means it fades out as oestrogen surges. When oestrogen peaks, it becomes quite faint and then fades back in.
Oestrogen levels rise and surge 1 - a few days before your LH surge. The LH surge triggers ovulation
At the beginning of your cycle you will have low oestrogen and LH (hopefully - some conditions can mean this is not the case). The CBFM measures your baseline levels and then compares to these. If you do have low LH and oestrogen, you'll see a dark line furthest away from the end you pee on and a faint or no line on the end closest to pee end.
When your oestrogen surges, which tells the CBFM to read high, you'll see a faint line (or no line) closest to the end you pee on and a faint line (or no line) furthest away from the end on which you pee. The monitor switches from low to high.
When your LH (which triggers ovulation) surges, you will see a dark line closest to where you pee and the oestrogen line (furthest away from the pee end) will become darker, or non existent, as oestrogen levels should be falling at this point..
The monitor does measure against baseline (ie early in your cycle) and so it's important to trust it rather than what you see on the stick. It assesses the intensity of the colours of the lines. It should be accurate unless you have any conditions that mean that you have high LH or oestrogen levels early in your cycle.
HTH!