When she made over her bathroom, Jaymee from Jay Adores made use of that empty space above the toilet by adding in three shelves for extra storage stocked with towels, toilet paper, and other essentials.
Pinned for the idea. Not sure how much I like the extension over the toilet. If were to do, vanity top should be one piece, with no cut line. Also: Consider how much the extra counter space would be needed.
Slim House Bathroom 1 by Alma-nac ("slim" is 2.3 meters wide = 7.5 feet! This room is apx 5 x 5 + shower) *glass tile on half-wall matches shower opposite, clean lines, ledge with light + big mirror cabinet to maximize small size visually and add storage*