Enjoy your childhood while you can. When we were little kids it seemed to take forever for Christmas, Easter and birthdays to roll around. As you get older time seems to go faster and I sit here thinking, crap, Christmas is here again already.
There's lots of adults that are stupid and immature. There's lots of kids that are too but they at least are kids being kids. You sound pretty sensible for a young un, and you are still young, so enjoy life, learn what you can when you can, and just take things one day at a time.
Basic mathematics is all you need in life unless you want to become an accountant or work for the tax office. Just learn how to add and subtract so you can do shopping and pay bills. Get your parents to teach you how to use a vacuum cleaner (assuming you don't know now), how to cook, wash dishes, use a washing machine and general household things. Get them to take you to a post office and let you pay a few bills (their money and bills but you talk to the person at the counter). You can also learn to pay bills online and it's good to know how to do both.
I was lucky because my mum taught us kids how to do these things by the time we were 12. She never told us she loved us or even gave us a hug, but she taught us how to be independent.
One of the guys I worked with at the pet shop was 19 or 20 ish and didn't know how to use a vacuum cleaner. His mum tidied his room for him until he left home in his mid 20s. We thought he was putting us on when he said he didn't know how to use a vacuum cleaner. We showed him and he loved it. A few years after he left the shop he opened a carpet cleaning business
Being an adult is nothing special. You get treated pretty much the same as you do now except you can get into more trouble if you do something wrong (like Gary mentioned). But even as an adult, and older, you will still see yourself as a young person even when your hair is grey. I look in the mirror and see a withered old man but inside I still think of myself as someone in my late teens. You grow up and get old physically but mentally most people don't age much when they become adults.