The black couch is not bad. I would try something: what if you pull the sectional a little to the right, so that it is not squashed right under the window. Place the taller table behind the couch in the corner and put the shorter lamp on it...hoping there will be a duplex, or might need an extension cord...place the taller lamp on the right, should make both lamps about the same height now.
Also, if you make a collection, three is usually a good number, I would do another beautiful shelf display, to make it three just a little lower and to the left as the last one.
Perhaps add some pillows to your couch, maybe red or more coloured ones with the curtain shade in it.
Black is always a nice accent, it would not clash with a brown couch, but if you don't like it you could always spray paint your collection a dark brown.
If you don't like the space that the couch makes by the window, or not make baby get back there (I see a swing, I think), you could perhaps tuck a short,narrow side table there and maybe have another one right next to your rocker on the left by the window wall, then you can put a cup or a book there if the need arises. I guess you don't have a coffee table because of baby, but in due time a round one would look nice and has less corners for junior to get injured.
Hope that helps a little - keep up the good work!

Here some pillow idea from Potterybarn.

Hi They 'big black' of the couch just needs breaking up a little with some cushions - bright/natural - whatever your preference. I would switch the rug 90 degrees as it al looks a little squished into the corner. A little light in the corner by the window would help too. It's a good size space with all the basics; just needs a little softening, I think. Have fun with it, Dee

Simple fixes - bring the sectional into the room more by pulling it away from the wall; lower your decorative shelves; try a round rug; larger, more substantial end tables. I would want to change the window treatments to something more modern, that's an outdated style, sorry. And if you can afford new lamps, mercury glass lamps would be amazing with your sectional.

If you are willing to purchase new sofas, pull the darker neutral color out of the rug and find a fabric that works with that, if you like the rug, which is fine. Or instead of leather, consider suede, which comes in dark neutrals, or what appears to be kind of a khaki green in the rug, but it's hard to see. Leather is nice, but if you have a room that probably gets used a lot, it is more comfortable to sit on something less cool/slippery to the touch....speaking from experience...but that is subjective......The sofas could sit as the sofa is now, and if they "feel" less bulky, the end tables could stay where they are, and a different (square/larger) corner table could be used. Also, maybe a chest or something more substantial as a coffee table....or a glass table so you can still see the rug. The rug can be pulled away a bit from the sofa/s....the furniture does not have to sit on it, only a coffee table. Take one lamp, place it on the new corner table, and the other somewhere else, maybe another room...the small tables are not in proportion to the lamps. Maybe a floor/reading lamp on one end over the end table. How about a more substantial picture on that wall, something with some size. The shelves could be painted the darkest color, again, a neutral, in the rug and they wouldn't be so stark, and if you do this, wherever you hang them, they should be on a wall that no one will bump their head so they could be hung lower. The window treatment should be removed. How about an updated iron/metal, thick drapery rod with interesting finals, big ones, and stationary side panels in a light neutral, nice, but not shiny, more linen, fabric to the floor.......