Your coach is doing the right thing. He is building you to be a very good runner in a couple of years. A guy with your speed who can run a 5k is deadly at a nationals type race. You won't do anything in the 800 with that speed and you can be mildly successful in the 1500/mile. I suggest talking to your coach about trying to run some 1500/miles this year but keep training the way that you are. Your junior year you will be ready.