Most major school systems have been addressing this problem for many years now, and have specific tests to see whether somebody has one. If you think the schools will not be helpful, you can see a neuropsychologist, psychologist, or psychiatrist, who also would be able to provide the same service (they developed the tests in the first place). What is good about these tests is that they identify weak areas, and may be able to help develop strategies to overcome, or at least work around them. Of course the tests aren't perfect, but they are often very helpful. My personal advice is that the results of these tests be seen as advice about how to get on with your life, not as a reason to give up on learning.