Minecraft 1.13.1 Villagers won't breed
The two things that would prevent a villager from breeding would be:
- Not enough doors: If there aren't enough valid doors, then the village is at its 'cap' and no villagers will breed
- Not enough happiness: If the villagers aren't happy, they won't breed. You can increase their happiness by trading with them.
Once you trade with the villagers a few times, and double check to make sure all the doors are legitimate, you should see them breed.