Autism

Dude, sounds like as really shitty time. I can see from your post history that you've had a bad run with communities (r/autism and their rule enforcement bullshit) and also a consistent theme of not having a very good home life. It sucks and being upset about it is the right first step. No problems there, this does suck, and you should at this point feel bad about it.

That said, that is step one. Your emotions are telling you that things are not OK, so it is a good time to listen to them. That does not mean letting them make decisions though, just let them inform you about your needs.

So next step, you need to know more about autism and ADHD. You will have this brain for the rest of your life and learning how best to use it now will pay off for your whole life. Learning that something is bad for you now means you can avoid it forever, rather than just trying to tank it and be OK with suffering it.

I have read you have seen a psychiatrist. Have you had meds for ADHD yet? Did you try methylphenidate and dexamphetamine? Did you try other meds? I found that dexamphetamine did very little for me but methylphenidate did a lot, so I ended up on Concerta and additional Ritalin in the afternoon. Your experience may be very different to mine but trying a few things is a good idea.

As for your parents, damn dude, having shitty parents is honestly awful. It is not your fault that they are shitty, that is a them problem. You need to take care of yourself and it seems likely that will mean getting out as soon as practical. Given that you are in the EU moving should be fairly easy, and given your English skills you should be able to function in a lot of different places. Maybe focussing on moving in a couple of years could make their bullshit a temporary inconvenience rather than the end of all things? Whatever they think is just their opinion, it is not fact, so if they treat you like shit they are not showing that you are shit, they are showing that they are the kind of people who treat others like shit. You can get out, it will take time, but it can be done.

As for how to manage things now, I would recommend emotionally divesting from your parents. They say you are a junkie for smoking weed? Don't fight it, just say OK, accept their opinion is their opinion, you don't agree with them, you don't need them to acknowledge that you are not a junkie, you can actually just let it go. You are the person who will decide on your values and make your choices. If they want you to be a certain way then they are welcome to be disappointed. You'll live.

There are some books which may be helpful but they are all in English, maybe there is one in Italian which is easier to really understand for you. First, have a look into parenting. Learn a little about attachment theory, parenting styles, and how good positive parenting is done. Once you actually know a little you can look at their behaviours and evaluate their performance. I would also recommend learning about narcissism, trauma, and cptsd.

Given that you are young and don't have decades of wealth acquisition behind you it will be challenging to move. Consider what you can do to earn some sort of income and develop your earning capacity. Obviously university is a great option depending on the field you are going into, but if it is not working out maybe look at whether you can finish up with a lesser qualification than a bachelor, say a diploma or advanced diploma. In many places this is basically equivalent to half or two thirds of a bachelor and allows you to finish more of your education later but enter industry now. That could shorten your path to financial independence significantly.

Regardless of what you do, there are options. Some of them suck, some of them are risky, and most of them are hard, but you have survived however many years being undiagnosed and mistreated, you are strong enough for this. Reaching out to other people for help is a strong thing to do and with that reaching you can build a good life for yourself. Don't sink into a depression because you can't get out right now, focus on the path you can make out and make active steps in that direction. You can escape fascist Italy and you can make a life for yourself, meet cool people, have friends, have relationships, and do cool stuff, it will just take time and persistence.