That sounds somewhat like my older DD. She is anxious, but not technically diagnosable as GAD. But she has greatly benefited from CBT, meds and other interventions. However, not until she was older. At age 6, it seems perfectly reasonable to take a wait and see attitude.
DD also has ADHD-like symptoms at times, but her therapist and psychiatrist both think this is from the anxiety, not ADHD. The test taking issues for your DS could be part of the anxiety. He could be too anxious to settle down or copes with the anxiety by acting like he doesn't care if he finishes. It's hard to say and I would wait and see how this plays out.
Do you want any services or just accommodations? If you only want accommodations, you can ask for a 504 and the school likely won't do it's own eval--at least ours isn't. It is faster and seems easier to get because it doesn't cost the school much money (no services). We do have an ADHD dx though.
DD has a 504 plan that gets her accommodations at school, but she does not need intervention or different curriculum or a different classroom placement. I think those are the issues that schools tend to really fight. Her accommodations are about managing and reducing her anxiety, none of which costs the school anything, so they are pretty happy to do what we asked for.
As I said, she does not have diagnosed GAD, but her psychologist wrote a carefully crafted letter that implied she has GAD but did not state that. Based on this letter, we were able to get the 504 easily. But we did not get the 504 until third grade when it was pretty clear that she was not in step with her peers emotionally.
I think a different type of teacher will make a HUGE difference for him. I know it does for DD. A teacher who is organized and calm goes a long, long way to helping DD keep control and manage in the classroom.
Beth, mom to older DD (8/01) and younger DD (10/06) and always missing Leah (4/22 - 5/1/05)