I've never lived one place more than 4 years, so I know how you feel. Unfortunately there's no easy fast way to meet people at that age except school. If you are lucky there is a local all ages club where you can meet people. You will definately find some heads there. Other than that, sports that start during summer is your best bet. If you have a local nature park they may also be a spot to find some stoners, but certainly not as solid as the above sources.

Good luck to you, and you know there is always this online group of friends...