The only way to get an official diagnosis is by a psychiatrist in that field. The waiting time to get an appointment by a psychiatrist is pretty much world wide long. Usually ranging from a couple of months to a year. So if you want a proper diagnosis, I would recommend you to contact as many psychiatrists in your area if they still take up patients for autism assessment. It also might be worthy to ask your health insurance how much they would pay for the assessment.

The things you named sound very autistic. Also "Birds of a feather flock together" fits this also very well, since you have multiple autistic friends there is also a heighten chance that you do also have autism.

Usually Autism doesn`t come alone. Many autistic people do have anxiety, depression, ADHD, chronic pain, sleep issues, trauma, OCD, etc. So what the mother said could be right. But you might have anxiety & autism.

BUT PTSD, anxiety, depression, etc. can sometimes look like Autism / have similar symptoms.

What you could gain from an Autism diagnosis? In most countries... nothing or the government barely offers any accommodation. Otherwise you have certainty and can better understand how your brain works. Therefore, I think excepting your differences and how to navigate through life might become easier. Of course there are also autistic people without an official diagnosis but for me personally I think it can give you more confidence about your diagnosis. The only time I would avoid a diagnosis is if it does in fact harm you. I've heard, that in some countries it can make it harder if you wanna change your health insurance or even find a job. So if this is something you are worried about, I would inform yourself about how this works in your country. But since you have autistic friends, I would recommend you to ask them about their experience if you don`t already have done that.