Mirror will look great when you get it framed out. I don't think it needs to be lowered - unless you really want a vanity light that will extend down too much.

I would look for a vanity light that can be centered in the space above the mirror; preferably with the shades not extending over the mirror or frame.

I like your sconce choice with your vanity and granite. :-)

If I were to move the mirror, I'd only move it down 1 1/2 to 2". For the hassle that would entail, I'd probably decide to leave it where it is. Good choice on light, the room is really coming together.

Hat tip to the lady who can hold her cameraphone around a corner and take a well-framed picture, too!

Two 3-light sconces you mean centered over the sinks?

Personally, I would do two ceiling recessed lights centered with each sink...but slightly behind you on the ceiling so it doesn't create shadows on your face. Then just one 3-light sconce centered on the vanity and mirror.