You do realize basically only high performing students take SAT subject tests to begin with? I’m not sure if you need reassurance, or if you’re just trying to humble-brag but your score is your score, and it’s a good one. If it’s not good enough for you then retake…but this is an obvious (and slightly annoying) overreaction.
Check the Georgetown results threads for the last couple years on this website. Lots of sub-750 acceptances. You’ll even find a surprisingly large amount of sub-700 acceptances, with 800s rejected.
Take a step back and think about it. Would you really think a kid that got a 750 instead of an 800 on their test to be less qualified for admission to their school? That’s a mere question or two different.