Photos?

pic is posted now

Consider a creative way to store your towels.

You just need to add the softer elements, towels, rugs etc. You can bring in color or if using white and other neutrals think texture, texture, texture.

A valance with color, pattern or print over your window would set off your tub. I like Color Zen's advice on wall paper too. There are so many wonderful fabrics and wall papers to choose from. You could also place a garden stool on one side of your tub and place a plant on top.

More photos will help us if you want suggestions.
Questions...
Are the floor tiles textured or matte-finished for non-slip safety?
Is the floor heated?
Do you need window treatments for privacy or is the window frosted?
Do you have hooks for damp towels to dry out on?
Suggestions...
Towels and washable bathroom rugs will add texture, softness, and color if desired.
Art will add color at eye level (glassed framed art).
You could place towel racks on both sides of the tub and hang art above.
Shelving painted the same white as the window trim could be useful IF they don’t get filled with stuff. Closed storage is always useful for extra supplies of everything.