Well, if you're already doing all those exercises...I give up! Just kidding.
Running, to me, is very intreguing exercise and what drew me to the Lydiard program is its logic. Amby Burfoot asked me once why I was so interested in the Lydiard system. My reply was, "Because it makes sense to me." Now not all people react the same way and some can get away with not doing everything Lydiard recommended; but I personally experienced a lot of what he had said and it made sense to me. Lydiard said, "Just because you can run long and you can run fast, that doesn't mean you can race well." That's the concept behind time trial. Now, when I say this, I can see someone might attack me but I'm just simply stating what I know. There have been so many examples of young people training, say, 10X400 in 57 seconds; something like that. He can run far, and fast, but not be able to break four minutes. You'll need to coordinate your training. I found out that just by adding 5k time trial, per Arthur's suggestion, my time came down from 18 minutes to 16; just for training. It's because my body learnt to run that distance strongly and evenly just by doing it. Not by running a segment of it fast and taking a break and back to running fast again...
I didn't mean to creat a new term "anaerobic time trial" but what I meant is; when you are racing, or doing fast time trial, the exercise will become anaerobic. The reason why you don't want to mix all the intervals and racing (in high school situation in particular) is because they are all anaerobic exercise. So if that's understook, you'll know that, in order to develop your anaerobic capacity, all you need to do is to engage your body through anaerobic stimulus by performing anaerobic exercises; that you really don't need to do any set workouts to achieve that. You can do intervals; you can do hill repeats (though I wouldn't necessarily recommend that at this point); you can race yourself to race-fit; and you can do lots of time trials. So, if you felt you're not quite coordinated during the race, it may ("MAY") pay to perform time trials for your anaerobic development.
NO ONE can train exactly the same way. Many people misunderstand it because Lydiard wrote down THE schedule that you have to follow it exactly the way it's written. It is only a guide. YOU have to determine what your strengths and weaknesses are and adjust day-to-day training accordingly. You may want to do 5X1000; you may want to do 20X200; you may want to do 3000m time trial... You seem to be quite observing; now you need to analyze WHY you're feeling the way you do; what's causing it; by doing what type of exercise you can improve upon that. YOU need to figure that out. NO ONE can give you explicitly what to do via message board or even e-mail.