
Welcome, After Hours !!! 
Glad you are here. I lived through many of the same things that you have, and did not even have a clue as to what was wrong with me until my daughter was dx with ADD in high school. But like many other people I didn't even stop to think that I might have it too. That is, until I began researching it a couple of years ago. I was utterly astonished at what I found. It was like I was reading my life story. I was tentatively dx about a month ago, but am not on meds until I see the psychiatrist in three weeks. I am looking forward to a real improvement once I begin medication. But I get a lot of support and guidance from this website. I feel really at home here. This is a wonderful place to begin changing your life.
Good luck and keep us posted on your progress. Cya on the board.
Peace,
Ladyhope~
after hours,
you said that you've never had anything wrong with you before or anything that you needed medication to maintain, and that you don't think that there's anything wrong with you. There's nothing wrong with you. Having add doesn't mean that there's somehting wrong with you, it's just the way you are. also, there are tons of people with add who aren't on medication. it's not like taking tylenol for a headache, it's only part of the many ways that people deal with add. I have been on medication for about a year and a half now, but it doesn't make me automatically "better." I still have trouble with organization and getting things done and time management and impulsivity and other things that come with add. If you read some more about the ways that people manage their add you'll probably realize that you've been doing some of these things already without realizing why. I wouldn't be scared about being diagnosed with ADD because the only thing that it can do is make you more aware of why you do the things you do and why you think the way that you do and from there you can do things to deal with it and also enjoy the benefits of it.
Hey! Welcome to our little neck of the woods! 
I could have written your post myself, up until last summer (until I actually started researching it more after a friend was diagnosed), I too believed it was more nutritional deficiencies, schools taking advantage of the diagnosis to use Ritalin as a babysitter etc etc. I actually did believe that ADHD fully existed, I just thought at the time it was way over diagnosed.
At any rate, I too was the same as you in school and college/university, but I just thought I was scatterbrained, lazy, unmotivated etc, even though I had great goals and big (realistic, but big) dreams for myself.
I always knew something about me was different, but I never knew what it was. The messes and total disorganization I would get myself into because of my ADHD, caused me to go into deep depressions because I felt like such a failure. NOW after doing SO much research and talking openly to my family about it, I realize what the problem was all along. My mom had it, my uncle has it, my aunt has it, I'm positive my grandpa had it as well, so there is a strong genetic line of it in our family. Living with ADHD isn't the easiest at times, but for me anyways, just knowing exactly what the problem made it so much easier for me. It was like a huge weight was lifted off my shoulders and now I know how to deal with it better and work with it instead of against it like I did for so long. I'm also on meds (dexedrine 20mgs a day) and that has also been a life saver in addition to therapy - for the first time in my life I can focus and actually finish something!
Anyways, sorry for rambling!
Welcome to the board! 