Jonathan, as you say, you are still only in secondary school mathematics.
College and graduate school mathematics are far different than what you are experiencing. It is far more challenging, in an exciting and rewarding way. I recommend picking up a proof/logic book, such as Carol Schumacher's book "Chapter Zero". This is often taught at the beginning undergraduate level in a college math program (after calculus), and it will show you some of the basic ideas of higher mathematics that mathematicians use on a daily basis. The actual questions that mathematicians consider on a daily basis are more complex than the concepts discussed in that book (I did say it was an early undergraduate text), but that book provides the building blocks for the post-calculus mathematical mind.
If you enjoy what you read about in that book, it's possible that you might enjoy pursuing mathematics as a career (whether as an assistant professor at a teaching college, or as a foot soldier at the front lines of mathematics at a research university). If you find the subject mildly interesting, but the questions only appeal to you in an academic way and you could just as easily enjoy spending your time thinking about, say, issues in anthropology, culture, or the natural sciences, then you might eventually want to find a job less all-consuming than a research career in mathematics. You may want to find work at a teaching college, or perhaps not even in academia. Perhaps a more ordinary, 9-5 job with good benefits and no obligation to mentally carry your work back home with you, thereby freeing you up to think about whatever you want in your off-time, is more suitable for you.
Perhaps it's worth saying that choosing this latter type of work, especially after you make it as far as graduate school mathematics, is liable to be fraught with emotional risks... high-octane graduate programs in mathematics, like other STEM fields, are filled with vampires (among your peers) who will suck up the nourishing nectar of your 'inadequacies' with a straw... but when you get to the stage of bargaining with your adult life in your hands, you have to cut through the erroneous beliefs about 'worthy employment' that are perpetuated in this (somewhat dysfunctional) social culture and make the choice of employment type that will be secure and sit well with your personality and working habits.
Again, it's still early in the game for you, so these questions might be a bit premature. Keep them in mind for future consideration.