Autism diagnosis doesn't guarantee anything to you, like disability benefits or school accommodations.
You have to ask for these, and probably try hard to get them if you want them.
For school, I suggest asking for very few accommodations that you really need, perhaps just one or two to start with.
Then, see if you make better progress academically with these.
For disability, it is very hard to get benefits, and benefits are not much to live on, so it is better to think about what you can do to support yourself in future, better than poverty trap of disability benefits.
For severe anxiety, you should get professional therapy if possible, as that is going to screw with your life in many areas if you don't reduce it to a manageable level.
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Drain and plane and grain and blain your brain, and then again,
Propane and butane out of the gas main, your blain shall sustain!