You chose a perfect off white for a North facing room. I would do a linen look, lined. You can find a vendor on etsy who will make them to order. I chose a dark lavender, because it too, is perfect with North light.

https://www.etsy.com/listing/197302774/window-curtains-pair-of-drapery-curtain?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=purple+draperies&ref=sr_gallery-4-39&organic_search_click=1&frs=1

You can go in any direction with this combo, contemporary, boho, tradition…possibilities are endless.

If you're keeping the brown carpet, then wait until you get the couch because gray with brown is tricky. Not sure I would have painted your trim black in such a small room. Here are some natural linen curtains with your current room and with the trim painted white. In any case, please paint your door. wall color if you keep the black trim, trim color if you paint it.

The previous homeowners stained the 3.5 inch trim in that glossy espresso color. The room was previously a peachy beige with a burnt sienna accent wall.. it was gross

https://photos.app.goo.gl/hfCE9RwaxccNB5tEA