You sound like you're going to break down any minute. Seriously, please relax! If a company seriously cares about the exact wording of your answers, you obviously would not want to work there. Management consultancy is a load of stuff any intelligent and hard-working human can do, they just want to test your basic intelligence and reasoning and check to see if you seem like a sufficiently nice human. Don't sweat it that much, your live doesn't depend on what McKinsey thinks of you.