I'm so confused about the future; I hate it.?

I am 16, turning 17 in a few months, and in September, I will be entering the 12th grade. I will graduate and life will go on. Unfortunately, it's the life part after grad that's freaking me out. I have a deep rooted fear of being a cashier for the rest of my life and living with my mom well into my mid to late twenties. Now, some of you may think "That's not so bad, 25 and living with your mom, what's the big deal?" Well, when you have four brothers who don't seem to be going anywhere and you're only sister is four provinces away, it's a pretty big deal! Especially when the house isn't big enough for everyone to have their own room! 7 people in this house is just too much. I don't now how I do it sometimes. Anyway, I feel that life leading up to my graduation of High School, was extremely well planned out. First it's Elementary School, then High School and they eventually lead me to Life. It might not make sense to you, but it's how my mind works. Now, I don't know what I'm going to do after I graduate. I don't want to waste my life away doing nothing, but working at a grocery store and living with my mom. I've always liked school. I've hated teachers, students, cles, a lot of things that come with (High) school, but it's fun, and I enjoy it. If I try (not very hard) I can get good grades, I understand what I'm learning (except for Math). So, I wouldn't mind going to College or University. BUT! I don't know what I'd study, and if I don't go to Post-Secondary, then what other things can I do? Travel? Sure, but I'm terrified of new places. Especially if I don't know anyone. I'm not one for change. It's inevitable, but I prefer to stay as grounded for as long as possible. I could eventually start my own business. I love to read and make up stories. I could open a book store, or write a book, but who would buy my novel, who would walk into my store? I could go to a college and become a librarian, that's not a bad job. But do I really want to do that until I finally retire? I'm just extremely confused and scared of living a boring life not getting married, growing old and living with my mom. How do you have an interesting life? How do you meet life changing people? How do you live?! BTW, I'm most likely thinking wayyy too much into this, so don't take me too seriously, I know I don't. :)