So often in young children, early-onset bipolar disorder manifests itself in symptoms that resemble ADD or ADHD such as hyperactivity and short attention spans. However, the fact that you've experienced blatant manic symptoms like rapid thoughts and speech and extravagant shopping sprees sounds to me like you've got either bipolar I or II. It IS possible to have both BD and ADHD/ADD, but sometimes it's difficult to tell the difference because the symptoms can be so alike and intertwined.

My advice is to observe your attention span when you are experiencing a euthymic mood, and have no chance of being manic. If you find that you have trouble paying attention or completing tasks when you're stable, chances are that you might have ADHD or ADD. On the other hand, if you only experience these symptoms during mania or depression, you most likely only have BD. In addition, the fact that you are "speaking a mile a minute" and your head is buzzing since you've started an antidepressant is a good chance that you have BD. Many times, mania is sparked by an antidepressant. I don't know if you had BD before you started Lamictal, but if you didn't notice mania before that, it's time to start a new medication that won't aggravate your bipolar disorder.
-GatsbyLuvr1920-