What on earth did they say you had???
Autism
Sorry, but as someone who's almost certainly autistic, WTF is this about not letting you shower? That's not an issue of diagnosis - whether misidentified or otherwise.
ASD is a social disability, and it's one with a huge array of differences from the norm, both in type and in magnitude.
Your parent infantalized you. That's not because of your neurotype -- whatever it may or may not be -- but because she projected meaning onto the label you were given.
That's fucked up. I'm so sorry you were treated that way.
Yeah I couldn't shower, wash my face, wash my hair, style my hair, wash dishes, cook food (even pouring cereal into a bowl to eat dry), go outside alone, do laundry, have my own room (forced to share with a relative who hated me), learn about puberty when I was going through it (and the institution staff assumed I didn't wear a bra because I just didn't care about anything other than video games). I needed disgruntled relatives to help with all that, and they'd bully me in private as revenge. Wanting to be independent was ungrateful and spoiled, but being dependent on everyone was such a huge burden.
That sounds like such an incredibly toxic environment. That goes well beyond the kind of infantalization I initially thought, and is well into deeply controlling territory. You need support! Social support, and structural support. Do you have some? Friends? Support groups? People you can lean on, and trust to provide some kind of safety net?
That kind of abuse is scarring. I highly recommend grabing copies of books like The Body Keeps the Score and Complex PTSD: From Surviving to Thriving. There are audio books for each, which are really good, and they're available as epubs if you're ok with digital books. You should grab copies any way you safely can.
You deserve help and support. We all need it to grow up and survive. It can be hard to find, especially when we're hurt and suffering the injuries of abuse. We will often find the wrong people, and find it very difficult to identify and trust the right ones. But there are people out there who will respect, love, and nurture you. If you haven't found them yet, look for them, and don't stop until you find them.
They will change your life, and in ways you will never imagine. I promise you.
A place where you can rant to your heart's content.