Alcove Kitchen and Bath

One great problem with fitting in a kitchen or bath to tiny spaces, is the physical space that a room takes out of your house.  Consider taking a single wall of the house...perhaps the one toward the street, the north side or the side with the ugly view...and devote it to shelving systems, closets and alcoves, for beds, as discussed elsewhere, or for your kitchen or bath.  Frame alcoves like any closet.  Make them blend into the wall or make them a beautifully framed focal point with fabulous woodwork.  You could even cover the whole wall with drapes that open at the mid points of the alcoves.  This also deadens sound from inside and out.  You could go so far as to bedeck the spaces with beautiful columns and arches.
The point of one of these small spaces is that you are likely to live alone, as a couple or as a small and intimate family.  So, having a bath that is exposed to the room while in use would not be a big issue.  Guests may have second thoughts though...but think of the water you will save if guests refuse to bathe while visiting.

Get a nice ball and claw tub and put it into a closet with the long side toward the opening.

Put your kitchen counter and appliances along the outside house wall in one of the closets.

Another alcove might hide your toilet, turned sideways to save room if the closets are not deep.

 A beautiful pedestal sink with cabinets, shelves or drawers on either side wall inside a closet would give you beauty as well as plenty of storage.