What is the rest of the house like? Would you like overflow sleeping areas or more storage? If you can't raise the floor (and the ceiling?) you might consider building in some comfortable seating/storage areas that use pillows/cushions and play up the multi-level idea and make it look intentional. Similar in concept to the stepped couch.

I think your layout is generally good. With a one bedroom it's nice for guests to have access to the ensuite without having to walk through the bedroom. One thing I do notice though is that there is a lot of hallway/storage/circulation space in the center of the building (in the two bedroom portion) that might be better used as living space. You could pretty easily make the ensuite in the one bedroom larger for example. The wash house space seems unnecessarily large to me as well. You could push the wall dividing kitchen from wash house almost all the way back to where the toilet door is in this plan (you'd then have the toilet door open into the wash room to the right from this viewpoint rather than straight ahead). This would leave much more kitchen to porch access, which would be nice.

Should have added, this is the existing layout:

A very simple layout keeping the floor space within the kitchen, the WIP takes up a lot of space with not much gain, The broom cupboard could be moved to the Laundry/entrance, narrow. If the wall has been bumped out to the eaves on the deck side giving an extra 300 depth to the kitchen you could make the island 2700 x 1200 and all drawers. The wall of narrow pantry will hold all pantry needs and more, no deep cupboards to dig into. cheers