Here is the full list of all 12 AMY achievements worth 200 gamerscore. It takes around 10-12 hours to unlock all of the achievements on Xbox 360.
You have finished the game in Easy mode
You have finished Chapter 05
You have finished Chapter 04
You have finished Chapter 03
You have pushed an enemy onto an electrical device
You have finished Chapter 02
You have finished Chapter 01
You have completed a level without the monsters draining Amy's energy
You have found Amy
Avoid being seen by the enemy by concealing yourself in a hideout
Finish the game in Normal mode
Finish the game in Hard mode