If you are planning on having fire in the fireplace you'll need to replace the floor and ceiling with something inflammable at least 2 blocks out from above and below the fire.
Designwise, my personal opinion is that the house looks unsupported.
If it were built in real life you seem to have one corner totally unsupported, one supported by a 1 block wide dirt ledge, one held up by the porch which would put a lot of stress on it and one corner with a thin wooden pillar.
It would certainly be possible to build IRL using hidden steal beams and if you like the look then certainly go for it, personally I would prefer something with more visible support.
Maybe Iron pillars or 2X2 stone brick, netherbrick or brick pillars in all 4 corners (the dirt corner would only need a 1-2 block high "pillar").
And maybe either pillars in the middles of the long sides or a supporting iron or stone brick frame under the house.
i'm aware about the fire thing, i've got firetick turned off