I was diagnosed with ADHD my third year at university, and I remember feeling pretty uneasy about the whole situation, too. I went for therapy and testing because I was feeling like dropping out of university - it was too becoming too hard and too much and I couldn't keep up with my studies.

Once diagnosed, and medicated, it was as if a switch in my brain turned on for the first time! I pulled all A's in all my courses, and learned how to listen and take notes and study. It was life changing! I stuck with therapy and worked with a behaviorist to learn other coping tools and eventually went off the meds while still being able to focus and get my coursework successfully done. Fantastic difference!

I encourage you to push through the fear and anxiety, cause the worst case of not being diagnosed will still give you tools to help you get through things better, and will remove the question mark hanging over you right now.