Tonight I was in the coop around 10:15 PM and one of my Ameraucanas was in a nest box, when all the rest were sleeping on the roost. She was in the box at 9:30 AM and I didn't see her out of the box all day. I didn't know Ameraucanas went broody and she is only 9 months old. What do you think?
She's probably broody. Most any breed can go broody, although it's much more likely in some breeds than others.
Sounds like she may be. If you want her to hatch a clutch I would isolate her away from the flock. Give her somewhere comfortable, quiet and safe to set on her eggs and in three weeks you'll have something like my broody Ameraucana Judy, with her babies.