It all comes down to your district/state/nomination slate competition and if you don't beat them and don't get the TWE, it then comes down to how you stack up against others on the NWL. I've read reports of people on here getting an appointment with ACT scores of 26, SAT's at 1200, below average GPA, etc.. Admissions uses a formula to calculate your Whole Candidate Score, and this allows for candidates to compensate for not as good grades with better than average test scores, leadership, or CFA scores. So no, having a less than average GPA won't kill you, but your score is definitely lower than it would be if you had higher grades. Have you by chance received a letter acknowledging that you are 3Q'd in your portal? If you haven't it doesn't necessarily mean you aren't, because some RC's don't do it. And I have no knowledge about prep school admission (why they pick who they pick.. stuff like that). Hope this helps a little!