Welcome!
First off, I think there may be some diversity of opinion regarding what "otherwise normal" means. =)
Re your actual question: Many of us have afterschooled to meet needs not touched by the schools. You've already tried AOPS, which is a frequent favorite. We used the Singapore secondary curriculum (Discovering Math/Dimensions Math), of which the original non-CC version goes up through algebra II/trig, followed by Discovering Additional Math, which reaches some univariate calculus. You could also try playing around with MIT OpenCourseWare. There are OCW courses aimed at AP calc review for high schoolers, advanced/fun math topics for interested secondary students, and, of course, also full-on MIT math courses, the most comprehensive and organized of which are in the MIT OCW Scholar section of the site. While entry-level classes are the most thoroughly covered in OCW Scholar, pretty much any level of math that he might want prior to his college matriculation (whenever that may be) will be accessible in OCW somewhere. Also, check out the other resources for high school learners on the site.
https://ocw.mit.edu/high-school/mathematics/And rest assured, there are others (admittedly, not a lot!) who have been through this. The path is unlikely to be quite typical, but that doesn't mean that the rest of his experience can't be balanced and age-appropriate to him.
