Your engine has serious internal issues. Likely worn rings and leaking oil into the cylinders via the valve guides. I don’t believe a bad PCV valve or screwed up vacuum lines could burn oil this fast.
I suspect you don’t want to spend the money on a rebuild of this motor or even a change it out for a used motor from a salvaged car. 3 quarts of oil per tank of gas must mean a whole lot of blue smoke follows you everywhere. This should kill your catalytic converter off soon too.
Why not try an additive, it can’t hurt a motor that’s pretty much on its last legs as is. Continuing to drive this car this way is an envoirnmental nightmare. Either fix it or junk it, but it is irresponsible to keep driving it as is.