Adult ADD? What to do, what to expect?

I've always had trouble concentrating but I've never had trouble in school. In elementery school, the school nurses/counselors wanted to put me on ADHD meds and my mom said no. Middle school and high school were easy and I never needed to study for anything and when it came time for college, I crammed my way through it by sitting down the night before with a big pot of coffee and a pack of cigarettes and forcing myself to review the materials and read the assigned readings I was supposed to have been reading along with the classes. Now I am an "adult" and I find myself way too easily distracted at work and my boss suggested I look into the possibility of being ADD. I get my work done, and I do it very well, but it's very hard for me to stay on task. Like, I have to be reminded of what I'm supposed to be working on when I wander off and tinker with other things. My question is... How do I go about getting an accurate diagnosis? And if I am diagnosed with ADD, what kind of medication would I need to take? How often would I need to take it? What will it do to me? I'm worried that it will change my personality... because I like me. But I don't want having ADD to hinder my career path... help?