Charlie: The first, and most important thing you must do before you apply is to actually find out whether you have ADHD or depression. Many doctors these days can be very quick to over-medicate kids, and it's entirely likely you have neither. Find a psychiatrist in your area or get a referral to one from your family doctor. Mention your history of medication, and have them give you a formal diagnosis of your condition, if any.
If you do not, in fact, have either, then have your doctor or psychiatrist wean you off the anti-depressants. Get documented evidence that you do not have clinical depression or ADHD, when you stopped taking meds, any adverse effects etc. etc.. In all likelihood, until you are off anti-depressants and sympton free for a while (usually a year), the CF will not let you in. If you still want to join, wait until a year after you got off meds, get all the documents pertaining to your condition from your doctor(s), and present it to the recruiting staff performing the medical exam. Like I keep telling everyone; the more valid, documented evidence you have that you're ok, the better your chances. Just saying you're fine is one thing, but a formal letter from a psychiatrist saying you're fine is what they'll pay attention to.