When I was your age, I thought exactly the same thing. I decided to study calculus because that was the "most complicated" mathematics I knew of. I found a copy of "Calculus" by Harley Flanders, Robert Korfhage and Justin Price (1970). I kind of lucked out, because even today, this is considered one of the easiest to understand and most comprehensive books on calculus ever written. At the age of 13, I spent the entire summer working through it. Needless to say, I crushed high school pre-calc and calculus, when I studied them 2-3 years later. It also saved me time, because later on I could spend less time on math and more on other subjects. Ultimately, this effort was a factor in helping me get into Princeton, where I went to college. Princeton is the top mathematical school in the world.
Nevertheless, I would not do this if I had to do it over again. When I got older I found out that you learn a lot more if you study what you are interested in, not if you follow a textbook. What you should do is study problems that fascinate you, then only use the textbooks to help you solve those problems. Use your own intuition as your guide. Ramanujan, possibly the greatest mathematician in history, learned mathematics by gathering discarded kraft paper from the docks in Madras and writing on them in charcoal. He made up and answered his own questions--and that is the way to do it.
I would recommend starting with the theory of numbers, rather than calculus. There is a book called "The History of the Theory of Numbers" by Dickson, which you can get for free from Google Books. Learning modular arithmetic is probably the number one best mathematical skill you can acquire to start with.
For learning calculus what I would recommend is starting at the end, not the beginning, the end being partial differential equations (PDEs). PDEs are by far the most useful thing in calculus, allowing you to calculate any rate equation. This is enormously useful in physics and chemistry. Unfortunately, in a normal calculus curriculum you do not learn PDEs until the very end, often not until studying advanced calculus in college. I would advise starting with PDEs and going backwards from there. Whenever you get stuck on a PDE problem, work backwards to learn the foundational skills you need to know to solve just that one problem. Once you can solve any PDE you will have a really valuable skill.