Draw a sketch with existing layout and post it here, show the door/window location if present and few dimensions, etc. Without that what you asking is useless.

20 pounds doesn’t fit in a 5 lb sack. Any bath that is already small and cramped cannot be made to hold more without annexing quite a bit of adjacent space.

And what are the surrounding spaces that you propose to cannibalize for the bathroom? Are you losing a bedroom to get a bigger bathroom? What are the actual wall and window measurements? Doors? Plumbing locations?

Hi Sophie. The dimensions and window / door location is marked on the sketch I uploaded a short while ago. The currently installed bathroom is going to be ripped out and a new floor / ceiling are going to be needed so we have the opportunity in remodelling completely and altering the plumbing as needed. Our upstairs toilet is in a small toilet room next to the bathroom and we want to put a new toilet in the bathroom and use this small room to store vacuum cleaners, towels, bed sheets, etc. Hope that helps!

Rearranging your whole house isn’t a cheap project. Moving plumbing is not cheap either. If you actually have a realistic budget of at least 100K, then talk to a local architect. Structural alterations and systems changes need to be planned and permitted locally, by those who can inspect the current homes structure.

oh we're not thinking about changing any of the homes structure Sophie. Moving the pipes, if needed, shouldn't be too tough a job once the floor is up. What I'm looking for is a design that incorporates two basins, a shower bath, a toilet and storage drawers. We need a space so my wife can apply her makeup as well.

Moving a toilet is a big job and since you are not including that space in your new bathroom what you want can’t happen. Sit down with your graph paper and draw in all the things you want in there and see what you come up with.