Faces are generally asymmetrical, unless you are some sort of genetically modified superhuman. You should draw the other half of the face rather than focusing on getting everything lined up, it will look more natural and lifelike that way. When it comes to portraiture, to hell with cleanliness!

Or, at the very least edit the lightsource so that it's not also symmetric, to give it more dynamic lighting.

That's an art basic rule 

Is that a new rule?

You have to at least change the highlight on the eye.