Its an interesting conundrum about how much training to do Al. You've obviously got a lot of natural talent but you're also still growing and getting stronger. You've got decades to run and either injuring yourself or burning yourself out at 18 isn't sensible. You don't have to do all your runs at 100mph either
All about time on your feet Al. Use your race time prediction as your guide for the long runs as opposed to the distance of the race.
God luck
The Journey of 1000 miles starts with a single step