I have a villager breeder and have gotten several baby villagers from it. Right now, though, I'm not getting any villagers at all, even though I supplied them with enough food, and have a bunch of 'houses' close enough to them.
I just watched a video on what to do if villagers aren't breeding, and had done everything the narrator already, so he said to just wait if everything else had been completed, as it can take a villager 2 hours to recognize a village.
I'm wondering if maybe when two villagers make a baby villager, there's some sort of 'cool down' timer or something where they cannot have another baby for a little bit even if all requirements are met.
There's also this I found on the thread 'Villagers still not breeding':
Villager breeding is an incredibly slow and tedious process - they don't enter breeding mode simply because they've fulfilled all of the criteria. Once the villager meet the requirements to enter Mating mode, they will occasionally and at random enter it. It's an infrequent occurrence at best, and then when you consider that two villagers have to do it simultaneously? Well, that's why the other questions on this topic indicate that it's not a fast process.. There's a saying: "A watched kettle never boils", and it's appropriate here. Go do something else while you wait...
Is this why it takes so long normally, even though the weird part being they'll breed instantly if I trade with them?
Also, I am in 1.11.2, Vanilla.
EDIT: Just went back to the breeder and the hearts were flying! Took a while but now they're breeding, which makes me think as the quote above stated, even when all criteria are met, it can take a while for breeding.