Iron Farm not working??? Tried to make it on my own.

I basically used whatever I learn from and iron golem spawning mechanism video to build this. I filled in all surrounding caves with dirts and turned the land above the iron-farm (it is build under ground) into path dirt. It was working for a while and I ended up with 2 stacks of iron-blocks, but it stopped working and I've been trying to figure out why.

1. I broke and replaced the beds.

2. I got rid of these villagers and replaced them.

3. I also moved the farm 10 blocks lower.