Only way to know is to wait two weeks and test. It would be advised that you don't get so drunk though. If you live in the states, and your age is correct, it's illegal-not to mention even if you are above the legal age you should never put yourself in that situation. You don't know if the person you were with has a clean bill of health, you could get taken advantage of, etc. Good luck. Remember if you don't protect yourself and your personal health, no one will.
If you are really that worried about it either take a test or make an appt with the ob-gyn...I used to be on the depo shot as well and have had unprotected sex but never got pregnant...I think you will be okay but for assurance check with your doctor or take a test..hope this helps you