You could do a wet room on the south end of the room with the tub and shower combined to conserve space. Window would go above tub, however with privacy in mind it would not be low as you have in your cad drawing. see photo. Vanities would go on the west wall with toilet on the east wall. I am guessing at the dimensions because you mention meters and in the US we use feet, but it sounds like about 9'x15" ? The location of the entry door really impacts the layout of the room, but it looks like it cannot be moved.

A 3x3 shower is too big. Definitely less intimate. I like the second plan! What did you decide to do?

Personally, it's better to have a wall between the bathroom and the toilet so no one gets walked in on. Definitely a good idea to keep the bath in case of reselling, although are you planning on going anywhere? If not, get rid of the bath and get a bigger shower I think.

We have a 900x900 shower and it's plenty big enough. Neither of your proposed layouts looks that great, to be perfectly honest, sorry! In the first layout, you could improve it quite a lot by swapping the toilet and vanity (centre the toilet under the window on the bottom right of the picture if possible), and having the shower door on the other wall (beside the door). Then, you could have a towel rail on the wall beside the door (i.e. behind the door when it's open), which would be accessible from the shower but hidden when the door was open. An 800x1200 shower might be a good size for your space. You'd have to choose a toilet that doesn't protrude too far, plus a narrow vanity. With that layout, you could have a long but narrow wall-hung vanity, with a big mirror covering the wall between the windows, which would make the room feel bigger and would give a good amount of storage. Also, you may find this helpful: http://www.houseplanshelper.com/small-bathroom-floor-plans.html?utm_content=buffer4aa20&utm_medium=social&utm_source=facebook.com&utm_campaign=buffer