I hesitate to interfere in the training of a high school kid, as I'm sure your coach is doing all he/she can to bring you along.
But here's a few questions you might want to ask yourself.
1. WHY am I running?? Because I like running, or to find a girl, or to just make a team...ANY team.....or to make myself a better, more disciplined person?? Some other reason(s)?
2. How did I FEEL after my three races?? Was I totally spent, writhing on the track in pain, gasping for breath....or did I jog off, talking with my friends, totally relaxed?
3. Is my intent to become an Olympian by 2016...compete on a Division 1 college team in a couple of years...or just get faster as I progress in training, establishing a solid "base", and let the times improve naturally??
In conclusion, and I would talk this over with your coach (and with yourself!), but I would advise you to become a STUDENT of the sport, start reading Track and Field News (if you aren't already!), listen to your coach, don't be afraid to lose (you can finish LAST in a race, and still get a PR--personal record), and just ENJOY yourself!!!
P.S. Forgot to ask, but are you a boy or a girl?? You didn't say! It would make a BIG difference in your expectations. If you're a girl, and running 5:49 for your first mile race, that's pretty darn good!!
If you're a boy, here's one example of why you shouldn't lose hope: Jim Ryun, once the high school record holder in the mile (in the 60's), ran his first mile in 5:38. Less than one year later, he had run 4:07.6. But not every boy is a Jim Ryun!! It's good to use him, and others, as inspiration, but NOT as someone you MUST emulate!!
Again, I say, just have FUN!! It's a GREAT sport!!