That is a LOT of Lamictal. I'm on 400 mg/day and that's supposed to be where it tops out. You are probably going to have trouble with balance and word-finding, if you don't already. I think a second opinion is definitely in order here.

And as for psych nurse practitioners, don't discount them entirely. These are master's degree or even doctorate level educated people who specialize in mental health. They are more than adequately prepared to diagnose and treat most MI's. I've dealt with a couple and they were every bit as good as my own beloved pdoc. Just so you know that they're a viable option.