What can I do to add more space to my small Bathroom?

do you have space behind the toilet for a storage rack

Hello needing more space for a small bathroom can be easily done if you have a place you can make more space in. If you do not want to change it structurally, like borrowing from an adjacent space, look for wasted space in the bathroom. For instance a access wall on a shower that could be made into shelves wile keeping access to plumbing. Also is there a closet in the space that could be re organized? Here is a closet door example https://www.pinterest.com/pin/406942516303174794/ Here is the converted wasted space from the shower wall https://www.pinterest.com/pin/406942516305345540/. Every bathroom is different and being very specific about what you end goal is helps to achieve it. Good Luck!

Containers on the walls above head height attached with the open side facing outward. Just so there aren't items you need on a daily basis. I love seeing baskets or metal containers wall mounted with towels rolled up in pattern fashion, toilet paper rolls laying the same way. Don't forget the little over-the-commode cabinets. My bath, off the master, is very small so I understand your dilemma. I was able to find a slim (6"width) 3 basket, roll-around that fits between my basin and wall with such exactness I was amazed. It's even an exact depth of my (small almost camper size) basin cabinet. But everything functions. I even found a skinny container for my to-be-washed clothes.

Over the toilet shelving unit, if you have a cabinet consider adding either more shelving inside or a tension rod, over the door shoe cubbies also provide extra storeage.

I use floating shelves instead of bulky furniture for storage and organizing my stuff- good luck!