You don't have to have the fireplace and bookcases flush. Here are some nice ideas for you:

I'm an artist, not an ID, but I am happy to offer my perspective.

You could add another mantle on top of the existing one...to bring in out more from the wall, and then make that depth the same one for your book cases.

Personally, I don't know what it would matter if the bookcases stick out more than the fireplace. But leaving some space in between the book shelves and the mantel would make sure the fireplace doesn't get lost.

You don't have a lot of room to work with. Any way I picture in my head, putting your tv on that wall is not going to look right, there isn't enough room. You could put it directly above the fireplace but that won't be a comfortable viewing height.

Have you considered an asymmetrical design?

Like...a bookcase on the left...with a caddy corner bookcase/shelving unit on the right for the tv/whatever else.