Maybe try a bath mat. You can get them in all kinds of textures from loofah to grass to rock. Maybe something like that would help. There are also these sticky foot pad things people wear to the beach, that might help.
If all else fails, maybe try the bath. She won’t have to stand on tiles for a bath.

I don’t really have any answers but my daughter was like this at 11 also. She would pretend to have showers and sometimes would go for a week without one. But at about 12.5 she suddenly started to shower every second day and now at almost 14 she showers daily. I think she just naturally progressed with maturity. I wish you all the best! X

Have you tried a mat for the bottom of the shower? Or a towel?

No answers for you sadly, just wanted to say you are doing a great job mumma !

What a tough time to be going through.

That is a hard one – is sitting/laying in the bath not an option?

I have seen a fake grass type shower mat? Or what about the reef shoes?

When looking for an OT, try finding a ‘Mental Health OT’ They will be more likely to help. In the meantime, maybe suggest that she have a sponge bath? Or what about taking her to the local pool and getting her to shower there after a swim? This is a tricky one. Remember to get support for yourself as you navigate this parenting journey.

As someone else has suggested, have you tried a bath mat? Maybe take her shopping with you for one and let her feel them and see if she likes the feeling of it. There are some nice soft ones, but of course will depend on how she responds to the feeling.
Have you perhaps spoken to a professional about it? It may be useful if you haven’t.
Perhaps involve her in making the task more fun, see what she would like? Perhaps bath bomb shopping, bath crystals, bubble bath, shower bombs, music etc.
Good luck. I hope you find a solution.

Have you tried a bath mat on the shower floor? I’ve seen one advertised that is used in the shower and looks soft underfoot. I’m sorry I can’t remember the brand name.

Talk to an Occupational Therapist. This really is an area where you’ll benefit from professional help.

A young lady might like a gift arriving via the post of Bath Bomb’s and Bath Oil’s and Flakes. and Bubble Bath. Maybe if you have a bath in the bathroom she would be enticed with these products. I’d add nail Polish and hand cream for a Pamper session. I agree a OT could help with a session or two to work out Individual preference to bathe or shower. Dealing with the feel of tiles vs covering the floor. Maybe a pair of beach shoes, Aqua shoes you can buy made from wet-suit material might be helpful. (Buy from Kmart, Amazon, Temu, Amazon etc)

We have always benefited from OT advice.

Yes, my daughters OT helps her with her sensory issues and feelings of overwhelm

An Occupational Therapist may be able to provide support.

I agree with the shower mat or a memory foam mat (with grip back to stop slipping). Make sure you hang it out after use, otherwise it gets mouldy. You could make it a calming experience with dim lighting, calming music, essential oils, to make it a relaxing experience. I bought for my teen a Colour Change Shower Bluetooth Speaker (at my sensoryspace), which really helped

I think professional help is needed before this gets away from you. An Occupational Therapist may have some ideas as I am sure they deal with sensory issues often.

Have you tried non slip shower mats in the shower and having a bunch of bathroom mats down when she gets out? It can be really hard. Family who are on the spectrum really struggle with similar issues, they don’t see what the problem is so it’s hard to convince them otherwise.
Maybe try easing in with flannels and a tub of warm water so she can wash the essentials in the mean time.