All I can tell you is YES YES and YES.

I am 41 years old and just started seeing a pdoc for my ADD.
Although I was diagnosed as a child, it's been many years since I've been on meds for my ADD.

It is never too late to take care of yourself. If in fact you do have ADD/ADHD it will impact other areas of your life, not just school or career.

I will gladly offer myself as a cautionary tale. From childhood to the present I've had major difficulties with school, jobs, relationships, friendships, and dealing with the everyday boring stuff of life such as housework. The frustration and alienation has, at times, been overwhelming. I spent years wondering what the hell was wrong with me, why I couldn't function as well as everyone around me. I've spent too many years of my life feeling bad about myself. When I think of how different the past years of my life could have been I want to cry.
Don't let that happen to you. Whether it's ADD/ADHD or something else, it's worth addressing your concerns and if necessary take action.