Thanks for your response!
The front right (from the street) is a sunroom with a living room right behind it. The front left is a bedroom that was converted to a library, by a previous owner. All of the bedrooms (3 total) are back to back along the left side of the house (one enters into the living room and two into a back hallway).
There are no steps to the attic, just a hole in the hallway ceiling. We've been toying around with taking out two deep back-to-back closets and putting a staircase in, since there is a massive space in the attic that would be, as you mentioned, perfect for an additional bedroom.