If your school has a math team you might consider joining. Students in our district can compete up even if they aren't subject accelerated in math. For example, we have several 7th grade students who compete in the AMC 10 (American Mathematics Competitions) a contest for high school students. If your school doesn't have a team, you might find contests offered at a local University. The AMCs, for instance, allow you to search for locations where you can take the contest. You might also try USAMTS which is open to Middle School studetns, and you compete individually on your own not through school. All you need is an internet connection. Finally, The Art of Problem Solving has many great resources and problems for math enrichment on your own; consider their Alcumus program it's free.