Take the federal loans your 1st and 2nd year and bank them. That’d add up to 12k, so, 6k per year, plus the 7.5k you’re allowed to take as a junior and as a senior.
You’d have to work over the summer and during the year to complete the amount expected at usc.
Do you know why your parents said that rather than spreading the amount over 4 years? Are they worried you’ll fail put after 2 years otherwise? Do they think you’ll earn scholarships for the last 2 years?