You are going to spend three times what you think. You will have to rip absolutely everything out including most if not all of the drywall (especially since this will make it easier to re-route all of your wiring).
Cutting the slab to run new plumbing is going to be a really fun adventure especially if your plan takes you through an existing footing.
Moving walls? Better make sure thats even possible first, are they load bearing? If so you’ll have to build temporaries and pour new footings.
Dealing with the city with all of this stuff, just shoot yourself now.
Adding on an entire additional master suite probably wouldn’t cost too much more than all of this, plus, your existing home will be operational.