Lilfae - I'm not 100% sure, but I seem to get better readings if I move my finger over just a smidge, so that it's NOT just the very end of the tip over the flash/camera. I don't know... maybe the edge of the tip is too "thin" and the light doesn't reflect enough?
Have you tried meditation at all? I've been trying to do a some. I feel good when I do it, but I'm pretty overwhelmed all the time - so I often forget or don't make time!