Marti, do you have a picture? That would really help.
I wish my bathrooms had a window that would open. I would have to see a picture to get an idea. Good luck. It will come to you.
pictures are worth a thousand words ... how about an inside mount window treatment?
try decorative window film I used them on a few of my windows they look great
Here is the picture, hard to see with lighting
One idea is to slide a 1 inch dowel rod through the curtain rod pocket, use a closet dowel rod bracket (they are plastic & sold in pairs at the box stores)on the adjacent wall. The dowel rod will dead end into the adjacent wall bracket & use a standard bracket on the window wall. We do this all the time in cases like this.
I love Becky Sue's thought. Here is a photo of a cute one from this months Kitchen & Bath magazine.