Thanks. I hope you can consider me both respectful and skeptical at the same time, because you may realize that it's incredibly likely that an uncoached 17:xx runner is spending time on LetsRun on a Saturday -- this not being a website totally on the radar of the casual runner.
And if you've tried this, my apologies for insulting your intelligence, but I've taught and tutored lots of young people in various academic subjects, and lots of them feel as though they should just "get" it or not -- because some students actually do -- but it turns out that many don't learn that way. And many, many thrive when they find what works best for them.
You asked about running, and I gave my answer. But still, when you get a coach, try to work through the same level of consistency and good methods that the coach provides as you approach academics. Again, you may have already done this, so I don't want to frustrate you. But still, even though you might not find academic success on the level your running peformance indicates, I'd be willing to bet my life savings that you can be better than you ever thought possible.
Good luck with everything. And if things don't work out perfectly, remember how great it is to improve and enjoy the process of improving every day.