Hi CabbageDad, thanks for the response. That's very useful feedback, I'll incorporate it into my training. I'm a regular at my school weight room, and I'm actively trying to make myself more of a physical specimen with good projection. At this time, I'm throwing long toss into a net in my back garden most days. At this point, Ivies are mostly a second option, and to be honest, if I had offers from my favourite D3 as well as Harvard, I'd take the D3.
Some hitting video should be up on the Google Drive by Wednesday. The adult baseball I play is probably pretty close to D3 competition, with mid-80s pitching and college-sized fields. Our club has "import" players every year, often from mid-tier D1 schools like Bucknell, who we scrimmage against. For perspective, my average at AAA last year, which I would think is about low D3 standard, was .425.
As for coaching infrastructure, there are resources inside my club, but the best coaching is found with private coaches in the London area. I haven't yet considered this, but I think I may have to start talking to one of them and arranging sessions. I'll get on top of that.