Renovering af badeværelsesgulv

I need to renovate my bathroom: I live in an Andelsbolig from 1924, the bathroom is 1/1.5 sqm and it works as a wet room. I mainly need to redo the floor, since it’s not draining properly (the highest point of the floor is the drain). I have some Portuguese mosaic tiles that I could use for the floor, but I am open to different options and materials. The room needs to be isolated and painted as well. I have no deadline, I was thinking about working on it mid September.