It’s all about the arrangement
This weekend I just moved to a new dorm room, leaving my over-sized room which I had before. I am still in the same apartment complex, but I moved in to the room on the opposite side which is the smallest out of the four rooms in the apartment.
Now, before I moved my room was nice and full; with the unused space all being walking space. How was I able to fit all this stuff into my new, smaller room? Simple: carefully arranging the furniture. I knew what I had and when I first saw the room, I looked over it for about half an hour and decided the final placement for the different furnishings.
It was designed so carefully that my former roommate that had this same size room swears that my room is bigger than his; but upon further inspection using a tape measure they are indeed the same size.
The trick is to carefully arrange your room to maximize the floor space and ascetics. In this way, any room can accommodate you and your belongings.