1.) You aren't the first to have problems with the depth perception test, and assuming you don't run into walls frequently, you're probably fine.
2.) My personal technique, which was just utilized at my annual this morning, relax your eyes, don't stare at the circles for any length of time, and take your time. You WILL eventually notice a very subtle difference. Take your time.
3.) Lastly, I've heard of people that have had problems with it that have been cleared hot to civilian eye doctors, who have a "better" test that is much easier...if it comes to that. Remember, I'm sure those MEPS SOB's were telling you to hurry hurry hurry because they had 12 million E-Dogs to do behind you. They did the same to me, the key is to take your time.