Here's the deal:
You need to incorporate workouts, QUALITY workouts throughout your training. Towards the middle of your base phase, do tempo workouts. 15-20 min. tempo runs, 400s @ tempo pace, 800s @ tempo pace, mile repeats. These should all be with minimal rest. Tempo pace should be about 30-45 seconds from race pace. Take for example your 16:55 5k. Your race pace (according to your 16:55) is about 5:26 pace. Your tempo pace should be between 5:56-6:05 pace.
Once you are out of the base phase, continue to keep your mileage up with your normal runs, as well as incorporating tempos AND speed workouts (400 repeats @ 5k pace, 800s @ 5k pace, and ladder workouts). Also, make sure you are doing strides after every NON-workout run (regular runs). Since you are in school, you will most likely be racing during this phase, so use the races as a way to see how your training is helping and also as a way to learn to pace yourself better... pretty much so you learn to race better.
The last phase of your training should be towards your more prestigious races (regionals, states, nationals if you're in high school). During this phase, you're still keeping your mileage up, but your speed workouts are becoming a lot tougher; shorter and more quality based. 300s, 200s, 400s, @ goal pace. There's a bunch more, but just to name a few. Taper towards the end of your season (maybe 2 weeks before or so) so you peak at the right race.
You will be fine. Most importantly, trust yourself and your training. Confidence is key. Good luck.