OPKs after birth

[Iluvu13]

I had a baby in sept and had a reg period about a month exactly after birth. I'm using OPKs and my question is (sorry I never tried getting pregnant before it just happened so I'm new to this) why is my line so faint ? I know on the box it says the T Window needs to be equal or darker to the C window but I'm getting closer and closer to my ovulation shouldn't there be a faint line instead of no line in window T