Several things:
A. Taking the test multiple times doesn't appreciably increase your score, or your standing in the eyes of admissions counselors.
B. Relax! It's only a test! Admissions counselors use the scores broadly to sort out people they don't think will succeed, but tend to focus very little on the SAT score when it comes down to the wire. Your GPA shows academic strength on its own, and that counts for a lot. The difficulty of your courses and extra-curricular activities also count for a lot.
C. Apply to a breadth of schools, several "more difficult" to get in to than your main choice, several "less difficult." I suggest applying to 5-8 schools that you would definitely go to if accepted.
Best wishes! GT is a great school -- 7 years ago I was accepted there, and at VT, Purdue, Univ. of MD, and Johns Hopkins, ended up attending Univ. of Delaware, and I sure didn't have 1600s on my SATs either!
--Chris