What do I do if I want to take the AMC12 exam next year but my school doesn’t offer it currently?
Contact other schools that offer it and ask if you can take it there, I believe some local colleges offer the tests as well. On their website is a thing where you can find nearby testing locations
If you look around on the maa website there is a section that shows locations near you that offer the AMC. We found those and called around and asked if our son could take it. Many schools will gladly let you do it.