You will want to get testing done by a neuropsychologist. It can be quite expensive and insurance will not always cover it. I’ve found it best to call the neuropsych’s office and ask about what billing codes they use and then see if your insurance covers it.
Also ask what the testing will entail (you will want not only a dx, but recommendations) and when you can expect a written report. (Six week turnaround seems adequate. I’ve seen it take 6 months to actually get a written report).