If OP told us that no one from his/her high school was getting into T20’s, no one here would blink an eye. That’s rather common.
But OP, who wants to try for a T20, is telling us that strong applicants from his/her high school aren’t even sending any students to state schools with 50% acceptance rates. That would be a bit of an oddity. Granted, it’s a new school, but as state schools are more apt to value applicants stats, this is worth investigating a bit, to the extent it can be done without violating anyone’s privacy.
Whether or not it is too late for OP to try and do anything about it (maybe, maybe not) is another question.