Be aggressive calling and emailing the RC and HC, and it would be helpful to have your club coach or high school coach call specific schools on your list on your behalf. You've been throwing, so it's likely you could be in a good position for a winter camp, which is odd for a pitcher given customary shutdowns and ramp up times. But congrats on the move to pitching.... keep working it, get stronger.
As mentioned above, one year at a JUCO could actually make sense, then you'll have the time to position yourself for a higher academic school - Ivy. 6-8 months of refinement and strength gains given your size, you could gain more "mph", really making you attractive. Also, just for reference, there are a lot of kids that go JUCO or a military prep schoool to be able to get into a service academy...
It's late for service academies for 2018's but not impossible. D1 ball, they pay you to go to school.... just throwing it out there.....
If you really want to play ball, or leverage your pitching abilities to a top school in the country, one year of positioning could be a smart route.
(plenty of regionaly D1's will pick up players during spring HS ball of their senior years, but they're not necessarily the highest academic, but they're good schools and they might offer a lot of money)
Rambling on....enjoy the day all