Did your parents agree with this way of schooling? That you were too smart to go to school? That's the only way I could see this happening. Did you study when you weren't at school, or did you simply chill out till test time?
For some students and some schools, being in school is actively bad for them, even worse than a fairly useless homeschooling experience. Some schools are just that bad.
The hard part is getting into college. You can take a test (the GED) that is meant to certify that you have an equivalent to a highschool education. Still, without a transcript, you will have to lean a lot on your resume (jobs, volunteering, internships) and personal statement.