Okay I was going to say that you can run really a lot of intervals and do like 18-20 miles a week, but 7-11 is way too low. At least get up to 25mi/week running 5 times a week. But really don't kill yourself with intervals. That won't help you in the long run. Yeah build to there.
And put on some weight. Somehow. I know a lot of runners look like twigs, but 88lbs is kind of low. Especially for a young teenager who is developing