Lamotrigine seems like a really weird choice for ADHD…. I’ve been reading some psych meds discussions elsewhere and Lamotrigine comes up a lot, but never for ADHD. The Wikipedia article section on its off-label uses does not mention ADHD.
It’s an anticonvulsant that is mainly used to treat epilepsy, other seizure issues, and bipolar.
Have you tried Wellbutrin? It’s an atypical antidepressant (NDRI) that’s often used off-label for ADHD. I recently started taking it when my seasonal affective disorder got out of control, and I’ve found it quite helpful for ADHD symptoms as well. Unlike Strattera (which is an NRI), Wellbutrin also works on dopamine, so it can have similar effects to stimulants, but works very differently. Worth a try, at least.