Use a wall mounted toilet - it requires less depth since they only project about 20 inches from the wall compared to 28 for a std toilet.

Put the shower and sink on the shorter wall & you can limit the shower to 32" deep and put the toilet on the ajacent wall (shower side) in the remaining 38" space but shifted away from the shower. If the shower is 32 x 32, that leaves room for a 24 inch vanity on the shorter wall. The door would be across from or adjacent to the sink/vanity.

Did you look on Houzz for pics of small bathrooms for ideas? I know I've seen some that were really tiny, but it all worked. Having said all that, it doesn't make sense to do it if you are only thinking of what the next owner "might" want.

make the whole thing the shower ...

they are called wet rooms ...

see link ... as an example ...

ken

Does the current arrangement meet code? Can you draw the room with door(s) and window(s) on graph paper?

Take a look at on Houzz at bathroom photos and filter for compact. I'd agree with the wall mount toilet and wet room suggestions.

Yes, but something will have to give, a little bit. I am doing a bathroom that is 4'0" x 6' 9" so it's long enough but I had to do an in-wall-tank-wall-hung toilet because of the shallow depth.

It really depends upon the current plumbing arrangement and which way the joists run and factors like that as to how much you can tweak the layout.

Thanks all for the suggestions. Here's a quick sketch of the existing bathroom layout. (sorry I measured incorrectly so the dimensions in this posts title isn't correct). It is actually 4'6" x 5'8".
The current arrangement does not meet code in that the toilet side to side space is only 24" and if I read correctly, code states a minimum of 30".
I just can't see how I can keep a shower, which would be a shame because later in life when our kids get older, they might need this extra shower.
Any advice appreciated...

Is that a window on the back wall? How in the world do you access the the toilet with the sink and shower so close? Is the shower open with just a curtain - and you have to step over the shower base????

I think my original layout will still work with the window in the shower. Put the shower where the toilet is and limit it to 30" deep (code) but it can be wider than 32 if the window allows. Put the sink where the shower is - 18 or 24 wide. Put the toilet where the sink is.

Maybe put the toilet where the sink is and then do a corner wall mount sink where the toilet currently is?

I would consider making the whole thing a wet room.

I have never seen this sink toilet tank topper in person, but someone who was talking about putting a full bath into a 5'x5' room mentioned it.

No idea what code would say and it looks like the sink is only useful for washing hands in cold water. Maybe that's ok if you have hot water access in the shower?

Here is a link that might be useful: toilet tank sink review

This is the kind of sink I'm thinking of.

Here is a link that might be useful: Corner wall mount sink

Like pal said you could make it a wet room. You could look for pictures of bathrooms on boats for inspiration.

When I did college visits with my daughter, one of our hotel rooms had a tiny bathroom. (Kellogg Center at Michigan State, if by any chance you happen to live near there.)

I wish I hadn't deleted the pics I took but I'll try to describe... front left corner was the door; back left corner was sink; back right corner was toilet. The shower was in the front right corner with a ceiling mounted shower head. There was a ceiling mounted track for a shower curtain and a drain in that area. When the curtain was open it was not at all in the way and the shower floor space just became part of the room. (There was no curb or step around the shower it was just one continuous floor in the bathroom.)

There was a teak mat in front of the sink in case the whole floor got wet. I don't remember but I'm sure the floor had to be slightly sloped toward the drain.

I wouldn't want it as my only bathroom but it certainly worked for our short term use and I think would work OK for occasional use.

Your layout above would not work with a walled shower because, as mentioned, you wouldn't have room to get to the toilet. But with a ceiling mounted shower head (so it sprays down, not out toward the room) and a ceiling mounted track for a shower curtain that you could push aside, it *might* work. Obviously the floor would need to slope toward a drain under the shower head.

This is one. There are lots of examples on Houzz. Just search for "tiny bathroom" or "small wetroom."
I see these in yhe tiny house movement where homes are around 200sqft. This one has some pretty bright tile, but you get the idea. If you do this which was also described above you will need to waterproof the whole room.

{{gwi:2132978}}

[Modern Bathroom[(https://www.houzz.com/photos/modern-bathroom-ideas-phbr1-bp~t_712~s_2105) by San Francisco Architects & Building Designers Winder Gibson Architects