I am envious of these improvements. I ran 5:32 in 8th grade, did it again in 9th grade, ran 5:20 in 10th, 5:06 in 11th, 4:55 in 12th, 4:25 1500m as a college frosh, and 4:22/4:39 as a college soph before injury. After 15 years out and a few years training I ran 4:20.8 1500m pr at 39, though I was not training for speed.
Bad or no coaching, many injuries, and my own ignorance were surely to blame for not running faster in college, though I thought I had a low 4:30 or high 4:20s in me just before the last string of injuries.