I was similar to you - lots of speed but no endurance. You just need to make sure you train the right way, and you will be a great distance runner. You got everything that's needed - good running form, lots of motivation to improve (otherwise you wouldn't post here) and still young.
If you train a lot with your team, make sure to always HOLD back during any interval work/tempo runs/long runs. Save that for racing! Especially as fast-twitch athlete that's very important.
A schedule for 40 mpw (that's a lot of mileage, you should be able to run quite a bit faster off that) could be:
monday - long run, 8 miles easy, around 9:00/mile pace (same pace for easy runs)
tuesday - easy 5 miles
wednesday - CV workout 3-4x1000m in 7:00-7:05 pace, short 200m rest + 3-4x200m in 45.
thursday - easy 5 miles
friday - easy 5 miles
saturday - race or tempo run, 4-6 miles in 7:40-8:00 or threshold intervals, 3x2000m in 7:20-7:30 (not 4x, instead do a mile warm-up and cd). follow each tempo run with 4x30s hill charges
sunday - off
you can add striders or pickups to any easy run, like 6x15s or 5x20s etc. no all-out sprinting, but doing a good solid effort at high speed working on turnover and form.
if you do 400s with your team, make sure to run them slower and try to do more reps - that's how you build your stamina (for example 15x400 at 105s is better than 10x400 in 90s for you). when doing 1k or 2k repeats, always end the workout feeling you could do 1-2 more reps with ease. same with tempo runs - keep breathing controlled, even if it means running slower.
the problem with running hard is that you train the wrong systems (anaerobic running, lactate tolerance) instead of what you need the most at the moment (endurance, stamina).
you truly seem to enjoy running, so make sure to run smart and results will follow. i advise against going out at 12:00 min pace, go out at 12:30-13:00 pace and then pick it up in the end if you feel good.