I live at my mothers apartment and visit my dad's every other weekend. I would much rather live at my dad's but there's only two bedrooms and I don't feel comfortable with sharing a room with my brother. There's nothing wrong with my mom's apartment or her at all, it's just the city it's in. It's a small one, maybe 15k people or so. I've lived here my whole life and I used to have a lot of friends. There's only one mall here though so I see my former friends a lot which has made me scared to go outside. I haven't been to school in about 2 years because of this.
I have autism so my mother won't leave me unsupervised for more than a couple of hours. It's gone so far that she had to stop going to work and is working at home every day now, so she doesn't make as much money as she used to. I feel awful about this because she can't enjoy the same activities as she used to and she's always working.
I start gymnasium (it's like high school) in autumn and there's only one in my town. My former friends will be there and that scares me. I have to take introductory classes to get grades since I don't have grades in all subjects. Now If I had all grades then I could go to a school in another city but I don't. If your local gymnasium has an introductory program then you're not allowed to go to another school that has it.
I don't want to make my mother sad or anything but it's just so hard to live here feeling anxious all the time.
I want to start by saying that those feelings of anxiousness will always exist about something in your life. Maybe these issues with your former friends have been a constant for a while now, but even if you avoid them you'll eventually discover that a new set of issues fall into your lap.
I don't mean to make light of your autism, but problems are a part of life. You will always have them, the key is to have manageable problems and not extremely bad ones. It is human nature to experience discontent now and then, and it helps to discover new interests and new people to spend time with to help you overcome boredom and letdowns.
Sometimes a change in location can help, at least for a while. It might do you some good to test your limits and step outside of your comfort zone a bit, and see more of the world. It's sweet that you're concerned about what's best for your mother as well.
I came from a smaller town, and it has its pros and cons, but so does a bigger city. You will find things you would like about a larger area - more opportunities, more potential friend options, and more places to go. But a bigger place is not as quiet, can be more confusing, and is packed with more people.
Whatever you should decide to do, it sounds as though you aren't far off from adulthood now, and with that you will have more freedom to decide where you want to try to live and spend more of your time. There's no shame in sticking to what you're familiar with now until you've gotten school out of the way, before making a bigger change in your life.