I’ve been feeling incredibly burnt out today. Because I teach myself every subject, I got overwhelmed for not knowing one thing, and have been stressed all day. My so called online school teachers don’t help me, the teachers at the ALC I attend say they don’t teach the subjects I study therefore I should cheat my way through school, which I would never do because education is important to me. Sure, most kids at the ALC don’t want to get into an elite college, but I am trying to make sure I get into my dream school. In short, I need motivation. I know getting into MIT or Caltech is a reach for me, but I have this gut feeling I will get into one of the two. It’s doable, but I think right now I need to hear kind words telling me it’s possible.
I know that might sound odd, but everything you are dreaming of is possible! 
Don’t worry that much about the future yet, and bring yourself back to the here and now… feeling a bit uncertain is totally normal (but I have to admit, that it is rather irritating that your teachers refuse to help you :/) and if you feel that overwhelmed right know, maybe you should take a short break? Go for a short walk, get some fresh air and you will feel much better afterwards 
Whenever I’m feeling particularly overwhelmed with work, I take an hour or two to relax. Maybe watch TV, or draw, or call / instant message someone you care about. Then I recenter and try again. Don’t try to study in long stretches; it’s much easier to take 50 minutes and devote it to focused work and then take a ten minute break, then work for another 50 minutes, and so on. A lot of college also consists of doing readings and studying class material independently, so know that you’re building good skills for handling a college workload.
College will be better in that you will have more accessible and helpful professors and teaching assistants. Is there any higher power that you can complain to about your online teachers? It’s not fair to you that they aren’t doing their jobs. But if you can’t, Khan Academy and Youtube videos can be really good teachers (even better than college professors, lol).
You have some big aspirations; just take things one day at a time, and soon you’ll realize that you’re in the best position you can possibly be in for achieving your goals.