Measure twice, buy once. I agree with creating balance on the fireplace wall with art on the right side. If you measure both the upper shelves, middle wall, and lower cabinets on the left and the wall on the right, you'll know how big to get the wall art. Since you're on a budget, look at local art, do it yourself, or try a thrift or second hand shop. I like art.com myself, but it's a little more expensive. Depends on what your budget is. If you go that route, frames can be gotten on sale at craft or discount department stores. Think beyond just framed art. Wall art can be plates, metal works, Target has round placemats that can be spray painted to match other items you have on the wall. Be sure to tie it all together with shape, color, or style. Either to matchy matchy or to different isn't going to give the room unity. Look at the big picture. Get ideas from this website by putting coastal cottage in the search box. Write up a wish list for yourself.

For balance, try placing a large "coastal"iece of art to the right of the fireplace. Pick up colors from the art for throw pillows. If space allows place couch oppposite the fireplace and/or move the sofa and loveseat closer into the corner with a square table between with a great lamp. A nice comfy chair in front of the art, with a small table and lamp between the chair and the fireplace will give the room balance. No coffee table is needed since the room is small.

Several options come to mind. First, your room will never look finished without floor length drapes on the window sets, hung from chunky rods attached above and to the sides of the window frames. As for the right side of the fireplace - perhaps it could be made into a sort of reading nook, with a couple of comfortable chairs, a table in between, with a good sized lamp on it. On the wall, a large piece of art that you really love, would be an idea. Another option would be to place a game table and chairs, for board games, puzzles, cards, crafts, etc. Good luck and repost when you're ready.