I might want to add that GT’s admissions for in-state students this year have been extremely brutal regardless of major. I have seen many kids with top GPAs, excellent test scores, and good EC’s get deferred or denied.
With this being said, AA for GT works in a very strange way (from what I’ve seen). Assuming that an individual, who is an URM, has slightly lower scores/GPA than that of the average middle 50%, is most likely either going to get in or deferred. This had happened to my friend, who is African American and applied as an engineering major. He had lower test scores/GPA than that of mine and he got deferred. (For any girls applying to GT, AA will significantly help you in the admission process because they’re evidently attempting to increase the number of female students at GT.)
Like you mentioned how your HS education isn’t the best, GT also heavily looks into AP exam scores in order to see if you truly are good at Math and Science. I believe that they wanted all applicants to officially send or self report their AP math and science exam scores to them for undergraduate admissions. Check their undergraduate admissions website for more information about AP exams.
In order to fully answer your question about AA, I think that AA is the tie breaker between applicants assuming that you have a similar profile compared to an another GT applicant. They don’t compare scores to the national average.
Additionally, you’re applying as an OOS and that’s going to lower your chances a lot despite AA.
So bottom line, I wouldn’t get your hopes up too high, although I wish you the best of luck! I would look into other good engineering schools such as Purdue as a backup school.