If you can't do wrestling or bjj, here is something awesome you can do:
Get jui-jitsu instructional videos from bittorent, youtube, google videos, dc, ect, and get a few jui-jitsu intructional books from your bookstore (like boarders), and practice em with you and your friends. Look for ways to improve you techniques, and discover new ones. You can practice anywhere with proper cushining, such as a tarp or a lawn. This is a great way to get good on the ground, and its pretty common among people who can't train at a regular dojo.
You will also learn ground skills for wrestling. Even though you can't do it now, your parents definatly won't be able to stop you by the time you're a junior.