https://ibb.co/NsW1CSc 

Clear basic plan

IMO no one should be using the toilet while somone else is in the bathroom so toilet rooms to me are just plain silly . As for the plan you posted it has none of the items you mentioned in the Ikea one for sure The basic plan IMO both the shower and the toilet room are too narrow to be useful

We only have one bathroom, and we want to ensure it isn't fully occupied when someone is just using the bidet or taking a shower

You have not clarified the actual inches! Get off the computer, draw and measure the available space, neatly, accurately and inform the blank space to the inch.

One person can use a sink while the other is in a shower, so your comment makes little sense.. As far as the toilet? It won't have ANY privacy in a bath this size, so wait a turn! or suffer.

No adult will be comfortable showering in a 29.5 wide shower- it's a broom closet, elbow bruiser.

https://postimg.cc/qzp2RXz1

https://ibb.co/GQVPbxf

Ref Pic of the corner and the shelf in the shower area : https://ibb.co/dLCS6Yz

Can you check your measurements?

Your drawing shows 13 feet in length

yes thats is correct ("The area measures 13 feet in length by 6.2 feet in width."