I am not sure what to suggest as window treatments are one of my own ongoing dilemmas, I am just scratching my head over the fact you think that the drop makes your bedroom look smaller.

Your bedroom does not look small at all, drop or not! I am rather confident I could fit at least 3 copies of my own master bedroom in yours, lol.

Yes you're right, the room is massive!

Lovely room, looks airy for me. As the wall and ceiling are the same color , room does not look smaller. Right choice!

You've made a nice start! It is a very large room! Any plans for other furniture? You can pull the eye away from the ceiling issue and draw attention to the focal point bed by grounding it with a large area rug underneath. The other rug is just too small to have any impact is such a large space. You might try making the lower ceiling a feature by covering it with shirred fabric and then add draperies where the slant ceiling meets the wall. The nursery below is a variation of the idea, but your shirring would just cover the slanted part. Would look gorgeous in gray silk.

The room pictured is a staged room, but we do have a king bed and mirrored side tables. We also have a dresser and a chest or drawers to fill the room. I agree on a large rug.

The room is extremely bright already but just to add so more pop of color I would try to find some sort of hanging plant holder to put some vines or flowers in. It would really bring out the white in the room. Also it’s always nice to have a desk in your room if you have extra space. You certainty have enough room for some sort of marble desk.

Also for curtains you could find something like these which bring the eyes down.

I think you could solve the problem with a seating area to give your eye something else to see.

I'd leave that room nice and empty and put on my roller skates every morning and have a ball. :-)