Strange how you
continue to make unsubstantiated claims even after the source contradicting you has already been presented. German air production is given
here. So aero engine production peaked in April, while airframe production peaked in May. And as previously cited, fuel and rubber production both went into steep decline in Q1 44.
Powder production peaked in May, while
explosives production peaked in June. And finally, you can't forget the logistics strikes, with German rail traffic going into steep decline starting
May.
The only things you got right were armored vehicle production (which matters not at all with no fuel to run them as proven by Wacht am Rhein) and the fact that once the reserves were worked off, there was nothing left. And the reason the reserves were worked off was because strategic bombing drove production beneath consumption before D-Day, and that plus the additional increase in consumption D-Day caused, used up the reserves shortly.
Indeed, the Americans were very self critical, as one can see from reading the Strategic bombing survey which goes into detail on all the things they should have done better and places where they outright failed (most notably in the attacks on ball bearing production, which turned out not to be bottlenecked). Yet the facts on what they actually
did achieve is right there, and your insistence on relying on the self-serving memoirs of Speer and Guderian instead explains a good deal.