It sounds like you expect yourself to have everything figured out. Life is simple but not easy. Believe me, most everyone I know does not have life figured out in the mid-twenties and early-thirties. Life is not a puzzle, it's life. You think, you have it figured out and then another challenge/curveball comes along (layoff/marriage/divorce/best friend dying/whatever).
As someone wiser than me once said, high school is probably the most structured experience you'll have unless you end up in prison. College is different (if you decide to go).
High school is a geographical coincidence. College is more your choice.
You only have two years left in your "term". If you drop out, your parents very well may decide to kick you out (as in, why should they support you if you're not supporting them [by not dropping out]).
Unfortunately, in this white-collar society, having a high school degree is almost a bare minimum requirement for being hireable (in some states, McDonald's will not hire non-HS/non-GED)
> I'm introverted and spend most of my time reading or obsessively working on hobbies like programming
As someone who is much older than you and very much has considered the possibility of dropping out (e.g. quitting my job), please consider what you will do for income if you are not in school. Are you active in community/open source? If not, why? What kind of brand/reputation in the open source community have you built? Enough to do paid consulting?
> But, I spend nearly every moment outside of school learning, just because I love to do it.
You're like me. You're using absolutes. Contradicting yourself. I'm guilty of those self-lies too. No one spends every moment learning. Otherwise, you would be learning that which would have a greater relative impact on your navigation of this world (e.g. organizing introverts together, taking the lead, social and other-ness).