you have space in the middle: I would get a shower stall and enlarge that bath. And work a storage closet/shelving in a pantry right there too. then I would put a banquette bench built onto that wall behind the island. Table and chairs /or added bench w banquette seat make a really fun spot. Once you get pantry storage.....remove the vertical pantry cabinets left of fridge....more counter all around perimeter and keep sink on perimeter. That middle area between stairs and kitchen is your place to maximize, then the back area with kitchen/banquette/sunroom will be so welcomed when you get it renovated. This is all dependent on budget , naturally.

I'd prefer to see the powder room switched with the laundry. It's not a great place for a powder room (privacy issues!) but I'm aware that you space is limited.

Looks as if you have only 9.5', or so, in width, so no space for an island, let alone one with seating. The first plan is similar to herbflavor's suggestion, and the second is an alternate banquette plan: