I am completely unfamiliar with DE in CA. I can only share what we did for our son with 2 different universities in 2 different states. Neither allowed DE except under very limited conditions which did not fit his needs. We met with the admissions office who ended up having to confer with the registrar in order to get approval. He was able to get approval to take the classes he wanted. He graduated from high school with credit for 300 math and physics credits. It was a good experience for him.
Where you decide to attend college will determine whether or not your credits will be accepted. Ds did not run into any issues with schools like GT approving his credits. (he did have to submit course descriptions/syllabi to some of the schools to review.) The schools which don’t grant credit typically allow taking a placement test to determine placement. Stanford has an honors freshman math class which has students who have taken similar math sequences as you describe. (a close friend’s dd who was more advanced than our ds took that sequence. Definitely a match for accelerated math students.)
If DE will not work, you might look into Stanford’s Online High School: https://ohs.stanford.edu/divisions/university_mathematics.html
As far as AoPS, number theory and counting/probability are the classes you could investigate. I would recommend attending a Math Jam. http://www.artofproblemsolving.com/School/mathjams.php? They als have WOOT which might appeal (do you like competition math?)
I also highly recommend looking into summer programs. Math Camp and SSP are 2 that I would recommend looking into. Our son attended SSP and absolutely LOVED every minute of it.
HTH