So he's a high school chess champion who's played in state and national tournaments, but is only rated 1200? That sounds a little hard to believe.
Back to your question, though... it's impossible to tell. Your strategy of developing your pieces towards the center, creating a battery, "destroying pieces", and then going for checkmate says nothing about your ability. All it says is that you understand a few basic opening principles, and like to kill his pieces and checkmate him.
Therefore, I would estimate your elo to be anywhere between 600 and 2800. In other words, you are somewhere in between a beginner and Magnus Carlsen (but probably towards the lower end of that range).
Try playing some standard length games on this site, and then look at your rating. That will at least give you some idea of your skill level.
Chess elo rating?
My strategy is to deploy my peices towards the center quickly, create a battery or two, that's opening, and than the midgame is destroy every and all peices I can, and than once that is achived, go for the checkmate. I think I could do better if I balanced destroying peices and getting my enemy checkmate.
My question is though, based off the last three games, what would my elo rating be? His is about 1200 or so?