They all work the same way, some are probably just a little more sensitive than others and show a positive result with less hormone (ie-earlier)
it could be just your body getting back to normal- take care of you, and if you start to feel unwell, or not yourself, go back to your doctor and make sure evrything is ok.
Babies will come, as long as you are ok- take care of you first.
All the best
el.