If your parents can afford 25K (stretching), and you add about $3K you can earn over the summer plus 2K over the year + 5.5K in federal loans, your total maximum budget is 35K. Not bad at all.
As of now, the only affordable school is SLU - it’s even 9K below budget; see if your parents would be willing to use some of the “saved” money for study abroad, or rent in a city where you get your first internship or a used car.
As of now, that is, before you get your FA packages from UIUC and GTech, GT is $14,000 over budget, and UIUC is $16,000 over budget. However, OOS merit scholarships were already announced, so unless many many students to whom they were awarded, turn them down, you can’t count on anything (as you said yourself.)
Did you apply to other universities which may be within budget but which may be a compromise between GT and SLU?