Take the floor mirror off the wall and use it in a bedroom. Plan on light blocking shades at all the windows. Have you tried floating the sofa in the center of the room?

Yes we have tried the sofa in the middle of the room and it is too big to walk around and looks terrible

Pull the sofa out of the corner about 6 inches. Move the rug so the front feet of the sofa are on it. If the TV stays there get a corner TV cabinet for underneath it so that it doesn't look suspended in space. Remove the mirror it's too wide there. You could turn it and put the bookcase in front of it. Hang the curtain rod wider than the window and closer to the ceiling. I like curtain panels with a subtle stripe or design. These are from ballarddesigns.com

I think it might look better if you centered the sofa on that section of railing, pulled away from the corner windows. Put a ficus in the window corner and a corner credenza under the TV. Add art above the bookcase.

I agree with pulling the sectional out from the window a bit and setting the legs on the rug. In your last picture, it seems there is really not a lot of space between the sectional and tv (which is hung too high). If you are sitting on the sectional, is the tv at eye level?

Get a corner tv cabinet to set under the tv to ground it.