Congratulations Ross!
Getting a nomination is a big step - this is the legal authority the academy has to offer you an appointment. Basically, you need a nomination.
All 3Q means is that one is competitive for an appointment - they have been told they are scholastically qualified (either through a letter from the academy or an admissions officer) they are physically qualified (by passing the CFA) and they are medically qualified.
Yes - each Member of Congress is allowed 10 nominees for each opening. How competitive that slate of 10 is the unknown. Top qualified pick gets in for sure - either by the academy picking or the MOC choice - but then the other 9 candidates compete against all the other applicants as a whole as a qualified alternate.
In order to compete as a qualified alternate, you need a nomination.
So you have crossed a hurdle - Congratulations!