Gray isn’t the best choice for North light, unless there is a hint of lavender in the gray. B.M. violet mist is one in particular.

Assuming you don’t want to repaint the walls, I would look for a fabric with the colors that do well in a dark space.

Keep in mind that prints look beautiful when you can see them fully. Roman shades will cut the pattern with every fold. Stripe would work better, IMO.