I did a web search on "how to set up a sewing room in space with slanted ceilings & got quite a few images. You have to just scroll down as the pictures with slanted ceilings are scattered throughout the images.
Like quiltingcandy stated above, I'm sure your room is finished by now & I'd love to see what you did with the space.
https://www.bing.com/images/search?q...IQFRML&first=1