Are you planning on replacing the sofa? The one you have now is way too big for the room. I would buy a rug that incorporates your color scheme with two love seats ( nothing bulky) that face each other, centered in the room. If you require a lot of seating, you could add two decorative accent chairs with the suggested layout ( backs toward kitchen)

Hi, I agree that the sofa is too big for the room now and adding a rug would only add a busy, tight feeling to the room.
I see that you have a television over the fireplace and am wondering if the blinds you have up there offer enough light control for your needs. Stripes are very hot right now and your windows would look great with some toned down strpe curtain panels. I might do one rod over the windows with a valance going all the way across and panels on the ends. You could have a panel for the sliding door to match.

With the weight of the couch visually I would do a cornice over the windows and use the same heavier fabric on a one way draw drapery

Did you start another post about these windows?

I recommend pattern on the windows (matching pair of panels) and an area rug and pillows to get some color and pattern going around the room. An area rug would anchor the sectional.