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.
Just because you like to use the inefficient resource conversion, which honestly puts you at an even worse economic position, and don't know how to use munitions doesn't mean everyone does.
I actually tend to convert fuel to munitions whenever I use the ability. So what if my enemy has armor, I have a ten squad Panzershreck blob and mines and bunkers everywhere. Plus some Obersoldaten and probably a Pak 43 to boot. And here comes my artillery.
Munitions beats fuel. You may need fuel to tech and build armor, but armor can be countered with manpower alone and is doubly vulnerable when munitions gets involved. Meanwhile the only thing that counters munitions is more munitions.