Size 14 (on the label) works for me, the waist measures at 36", the inside leg on the trouser is ~31" which is probably regular length, but the crotch hangs a bit low on me, and I wear boots, so I don't want the lower hem draped round my ankles. My normal trouser inside leg is 33".
I also have an old pair of size 8's, which I wore before I put on a bit of weight, which are about a 34" waist and a good inch shorter than the size 14's.
Can't you return the wrong ones ? I wouldn't trust the bundeswehr size numbers for danish kit.