All valid points but my main thrust regarding Germany inefficiency stands. Slave Labor wasteful in labor and resources. The centralized economy added to the problem, and I agree they were severely limited by lack of resources. They didn't have enough of nearly anything from resources to manpower (except perhaps coal) and were wasteful in many cases misusing what they had. The cruel raciest policies caused some of the most decisive manpower losses before the war even began. Much of the top scientific talent the allies had (Manhattan Project on down) were essentially political refugees from fascist regimes. The Nazi purge of talented manpower was had significant adverse effects on their entire economy, not unlike Stalin's purge of military leadership.
Indeed, I do not disagree with your point regarding forced/slave labour ... indeed, I agree with it entirely.
Manpower problems were, indeed, considerable ... but, strangely enough, in one area the Nazis (very unpublically) backed down from their pre-war policies ...
Pre-war = Kinder, Kuche, Kirche ("Barefoot, pregnant and in the kitchen" ... very loosely ... literally "Children, Kitchen and Church"). They fired almost all, if not all, female public servants (Doctors, Lawyers etc.) and largely closed the Universities to women (at least in "nontraditional" subjects ... certainly Medicine, Law, Engineering, Public Administration ... dunno for sure about Humanities).
War = Reversed rapidly and entirely. Women dominated universities by, IIRC, 1942-43 ... even Medicine, Law and Engineering ... women were encouraged to take up industrial jobs, and even served as Flak/Searchlight crews, many being killed "in the line of duty" in the latter role ... of course, it wasn't done in any consistently useful way (even the University enrolments would only have started coming online by the end of the war).
So the Nazis could bend to reality in some ways ... just not well enough.
Author, Space Opera (FGU); RBB #1 (FASA); Road to Armageddon; Farm, Forge and Steam; Orbis Mundi; Displaced (PGD)