Using wall space for storage in your bathroom really is the best idea to deal with a room that often is quite small but that needs to contain a lot of stuff. You don’t need to install heavy and fiddly shelves, however, to make the most of your storage areas. There are other, easier options.
For example, you could use light and easily purchased woven baskets to store things in. Fix them to the wall on their side, and you can stack rolled-up towels, store toilet rolls, or even pop reading material in there. Your floor space won’t be impacted and you can reduce the amount of clutter around your basin.