http://www.fns.usda.gov/school-meals/income-eligibility-guidelines
Look at year 15/16, a family of 3 can make $26,117 for free lunch and $37,167 for reduced lunch a year.
So if the total household income was under that you would qualify.
Another benefit of free/reduced lunch is that you would qualify for SAT fee waiver, 4 free score reports per SAT and 4 application fee waivers.
Our school also gives a discount on AP exam fees for free/reduced eligible students.
And the money your parents can save on school lunch could be used for something else right now.