Usually, ADD symptoms are present in childhood as well. I would recommend seeing a professional to rule out other possibilties. Alot of other disorders can cause ADD-like sympotoms. Depression can mimic alot of the symptoms -particularly focus related ones, Anxiety and Post-traumatic Stress Disorder can as well, also serious mental disorders such as Bipolar disorder and Borderline Personality Disorder.

As for ADD itself, there are many 'sub-types' and each one is experienced quite differently as it affects different parts of the brain.

I personally have inattentive type ADD, which involves what is known as "thought-blocking". Best described it is as if a cloud or fog descends on my brain and i can not think or finish thoughts or process information/sensory input at those times. Because of it, i find it hard to stay focused on even things i enjoy. I have had this problem since i was a child, but much more mildly. As i have gotten older, it has gotten much worse and that is because I am also Bipolar which does tend to worsen with age.

I have found that the only thing that helps me with this type of ADD is medication. But that is because I am unable to use my mind to effectivly make changes, because it is under a fog. Other types of ADD and other ADD related symptoms may respond better to things like therapy, I am not sure. Its worth shelling out a little money to a professional to find out for sure. You may be able to greatly improve your life, if you are armed with the correct information about yourself. Also you want to rule out or explore the other possible causes of your symptoms, as it can be extremely disruptive to experience a serious mental disorder without being able to help yourself because you don't understand what is happening.

Good luck