am assuming this is a concrete structure, when shifting service toilet to utility area, and if there are apartments above, then running extra lengths of supply/drainage lines & introducing a structural sink slab (if this is concrete) under the new location can be charged extra.. it will be easier to divide the 3rd toilet. all services will be already available. only, do check on supply & drain pipes capacity as load is increased on the same pipes which were serving one toilet earlier..

Unfortunately all your options require custom work: It looks like you need an 18" corner cabinet. You will have to modify the last wall cabinet on the left. As I am eyeballing it, you should be able to cut the last cabinet in the middle and then shorten the left section to fit the space of the wall next to the door trim. It's an option that makes the area looks symmetric. Or you can install shelves over the sink. I would not recommend it because it will take the looks away. And the last option will be to remove the last cabinet, shorten it so it fits over the sink and install a single cabinet where the double one was. This will leave a triangle space behind the corner where the two cabinets will meet. You can block the space under it. Hope this helps!

I would consider putting cabinets on the short wall where the utility wall is. Have your stove there centered on the area. Move the sink so it is centered on the long wall where the cooktop is now. Put the fridge on the end run of cabinets closest to the dining table. That will give you an L shape kitchen with a nice work triangle. If you have your heart set on an island remove all the wall cabinets and install a large island. This is not the style of your kitchen but it does show the layout I described above. L shape cabinetry with stove on short end, sink in the middle with DW to right of sink with cabinet above it for dish storage and the refridgerator on the end run so it is out of work triangle and conveniet to the dining area for serving or work triangle for prep and cooking. Island can be any style you desire. L shape with island and open across from island; you might consider this layout if you desire an island. Something like this?

A McSo. Couldn't the base of 15cm overhang be supported end to end with steel. As a single steel structure mounted on the larger cabinet area visible here. It should be sufficient for supporting the extension. Corbels will provide additional support but IMHO may not be required. Have you thought about an semi circular or a D shape counter to avoid sharp edges. Thanks, Nitin Cornerstone Designs, Bangalore.