Hi there, I sorry i was so busy lately. Today i opened your file and your problem is your model is not symmetric, To notice that do to the left-view with armature selected zoom close to the origin, and see how your mesh is a bit side way(too much meshes on the y-axis side toward the back-view).
There is so many things that are wrong on your file.
Here is some i found after a quick look:
- The mesh is too heavy, leave heavy lifting to the modifiers.
- Always apply rotation, location and scale to your mesh and armature before parenting.
- Make sure, before parenting all you meshes origins are in the same place.
- Name your bones properly, this help when debugging your armature.
- Get yourself familiar with the feature under w keys in bones edit mode
Please watch tutorials, they seem long but they help to know what is going on.