Thanks for posting! Even though your sofa seems extra teeny tiny right now, once you start filling the room in more, it will definitely come into its own.
I would start by getting a big area rug. A shag rug could add some coziness and upscale cute to the carpeted floors, and ones like this moroccan print rug are great because they go with almost anything (and would look especially nice with those copper accents.)
With so much open space, a coffee table is key to creating a nice conversation area. I would look for a round coffee table, which can take up some space without dwarfing the sofa you have established. Accent chairs could also be a nice completion to that little lounge area, in time!
Then, I think once you start adding more things like pillows, throw blankets, and wall art (plants, too!), your room will be looking great in no time and no one will ever stop to think about the size of your couch!