My pleasure! You do need to keep your FC at shock level, above 15ppm.
Are you vacuuming to waste and brushing your pool every single day? Running your pump and filter 24/7?
I'm betting your CC is actually above 0 but below .5, but you cannot read it unless you test at 25ml rather than 10ml, which wastes reagents and, as you suspect, isn't really necessary.
Have you been cleaning your cartridge(s) and making sure they don't have any holes? I don't THINK you need to clean them if the pressure isn't rising but holes require replacement.

You can also try "skimmer socks" or another brand in your skimmer. They are cheap and actually filter out a lot of junk. You can also consider a "slime bag" which goes on the return and captures far more--but they run $60 - $80 -- may be worth it.

Tennessee? My older son almost went to Vandy--Nashville's a nice town.