Problem was not lack of soldiers, problem was:
-Germany was huge and occupied countries were mainly hostile, making it actually 3 front war
-Lack of equipment, sometimes Wehrmacht had to borrow weapons from Volkstrum...
-Lack of trained soldiers, this was common for all sides, but if Soviet conscripts broke, there was room to fall back. If Volkstrumman broke, he soon met 'nice allied soldiers' and surrendered to them
-Disorqanisation, Germany had HUGE number of "divisions" becouse many so called political leaders tough it was good idea to create new "Elite-Panzer-Grossdeutschland-Leibstandarte SS Adolf Hitler-Freikorps" divisions without any equipment or men, meaning they had to be taken elsewhere, experienced German units were taken their weapons and given to Fascist militia, and none of old units were ever dispanded, creating illusion of army of 200 divisions to dictator surrounded by "yes yes man" while he himself was "do this, do that and simoltaniousely do this".
According to some estimates Germany did have 18 millions troopers, but only 800 000 of them were at front lines, meaning few superb units like 116th Panzer Division had to fight day and night while other divisions were completely inexperienced.
+Something that i always miss, forget or am unable to explain properly or get wrong, i have rarely made post that has not needed editing. In fact this yellow text was added via editing second after posting...
EDIT (another...): I advice reading "Berlin 1945" by Anthony Beevor, at least it made me understand just how complicated/confused/more fitting word situation was during last year of the war