Raspberrytorte,
Maybe (just maybe, I wouldn't know if you could in this case) you could ask for a second opinion. I'd say that right would trump that state legislation (but I could be wrong).
Is this kind of thing normal in much of the US or just in Wisconsin? Is it illegal or not (in some countries it is; attempted suicide)? You could also go for negligence, maybe: if she says that lamotrigine is bad for you and you took it as prescribed at the time, just before, you overdosed, that would seem like negligence to me.