You can probably get extra time for tests by seeing the department for students with disabilities. This is very common. When I was in university I had a friend who had dyslexia and she was able to get extra time on tests and assignments. You have to have an actual psychologists letter though.
Also have you researched study skills/methods? i went back to school as an adult. ALthough at the time I had no idea I had ADD, I did realize my previous methods were inadequate. Luckily I found this great book called The Master Student which I think was largely responsible for my success the 2nd time around.
http://www.amazon.com/Becoming-Master-Student-12th-Ellis/dp/0618950036/ref=sr_1_1?ie=UTF8&qid=1309461653&sr=8-1
I highly recommend it for anyone going to school.
REPORT ABUSE