Many bathrooms are pokey things, or odd shapes, as though they were added as an afterthought. This is often true in old houses. So how to make the bathroom adequate if not what you want, short of pulling the whole thing out and starting again? This can cost you thousands.
If the shower is set back against the wall far enough, you can install a washbasin opposite and leave the rest of the bathroom for whatever you wish.
Fit a three-sided pedestal basin in the corner. Have a cupboard under it for cosmetics and to hide the drainage pipe.
You can purchase sinks that fit snugly into corner spaces nowadays. They are neat and tidy and you can have sealant applied so no nasties can get behind. This will not take away from the attractiveness of the bathroom, but it is an idea to have someone who knows what they are doing to install the sink or it can turn into a mess.