This is impressive for someone who is 16. My Two cents would be to add a short demo. A 30 second gif or video with accompanying text that explains how to use this. Just some kind of demonstration on how your interface works and what to expect the output to look like. And secondly to possibly help with the over suggestion/under suggestion issue, the grammar and writing assistance should be a separate mode from the fact checker.
Again, I would love to know more about how this works in the sense of how does it determine facts, and as you alluded to in other comments how it avoids political opinions.
