The source of Dragons

[One Axe to Rule them All]

Back to the subject of dragons breeding. I think Morgoth created dragons one by one, as you see, he kind of "Improved" his model as he went on, to upgrade them, see how he started with Glaurung and then made winged dragons later, as he needed them.

Not to mention, after the war of wrath, there were more dragons as said here

The few dragons who survived the War of Wrath and the downfall of Morgoth and his stronghold, removed to scarcely inhabitated regions in the north and north-east of Middle-Earth. The Withering Heath in the eastern Grey Mountains was from then on ever a dangerous region as great dragons still prowled there.

Here it says that the dragons that survived the war of wrath went to the north and northeast and lived there for a long time, so there must have been at least ten to fifteen dragons at least left to go on for survival.

It says that there are a small amount of dragons left alone for a few hundred (i'm just guessing here) years, don't you think they'd reproduce and become a great army again? I know most of you are thinking, "maybe they killed all the females" but if I was killing great dragons, i'm not gonna stop and check the
plumbing to find out if i've killed all the females.