its not ideal, but I think it would work. if you're living in it try it out!
my living room is about 4x4, but with a 900mm corridor running along one side, making it 3x4 and it works fine.
i would convert the existing living to a bedroom, but cut off the rear "L" section and push it into the kitchen as a dining room & pull out wall between kitchen and sunroom to make that a living space.