Just stop your fuel math. After 2 schrecks and few mines you have nothing to spend ammo for (just nades but 15-19ammo/min is enough for them) -> fuel conversion all day long.
Nothing to spend ammo for? Are you kidding me? OKW has tons of artillery call in abilities that are excellent late game as well as the fact you need to keep upgrading your infantry to make them useful. 90 muni to upgrade Fuss, 60 muni for Obers, ect.
And fuel conversion isn't 100% efficient, you will still very much be at a disadvantage income wise.
Ignoring OKW fuel penalty is like ignoring fact that Soviet stock units are shitty or that USF have vehicle crews.