I'm a very similar, yet not so special case. I was misdiagnosed as being bipolar, when really it was a mixture of ADHD and then guilt from not being able to do my homework. I dropped out of high school, got my GED, and I am now 29 and also finishing up my Ph.D. in physics. About three years ago I was finally diagnosed with ADHD after my significant other pointed out a lot of ADHD-like behaviors that I simply took as quirks. Getting here hasn't been easy, but having medication now has completely changed my life. When it comes to certain types of tasks that were easy to get distracted from, I could maybe get two to three hours of work done out of an eight hour work day. Now it's more like seven. I'm infinitely more happy and satisified with my life now, since I'm not convinced that I'm just a lazy SOB for no reason.
I still get very emotional thinking about it, and I realize that my life would be very different had I been diagnosed sooner.