The painting above the couch is hung too high, but at any rate the painting itself should have more height to fit your space properly. The rug is too small; all your furniture should at least have the front legs on it. Generally, however, the larger the better as long as the rug is 1.5 feet away from all the walls. I'm afraid your lighting is all wrong. You need table lamps or a table lamp and a floor lamp to direct the light where it's needed, which is not up at the ceiling. Your furniture is very nice but the colors are all muted, as is the painting, and you need some livelier colors to give this room some personality. Find a large, gorgeous painting to hang over the fireplace that has a variety of colors in it, not just cool tones. A vertical piece would be best.

I would love to see to see a large painting over the fireplace, maybe 2/3 the width of the mantel. The mirror is off-center relative to the bench and also doesn't seem to be reflecting anything interesting.

I agree that the room would benefit from a larger rug.

I think the TV would make more sense over the fireplace. That is not my usual go to but the set back in the nook isn't working. I would fill the nook with shelving or a cabinet/built ins that bring its front to the same plain as the fireplace. The lighting in front of covered windows makes no sense. Shorter lamps would give you light where you need it and opening the louvers would give your room light. I would vote for removing them all together but I don't know if privacy is an issue. I would like to see a wider shot of the entire room I am thinking you have too much furniture in it. The bench under the mirror could be removed and maybe moving things to the left would give the chair more room. I am not sure how the table near the chair fits.