Lamictal and severity

I think a very, very important thing to keep in mind is how differently medications will work for different people. While it seems many of you have had horrible experiences with it, I surely don't think this is the case for everyone, including myself. I've been diagnosed with bipolar-II and have been on Lamictal for several months, currently at a dose of 150mg. I've found it had dramatically brought down my rapid cycling and decreased the severity of my depressive episodes. Though I still have mood swings, they are less frequent and less intense/disabling.
As far as side effects go, I've never been one to experience many side effects from any medication I've been on. With Lamictal I've begun having headaches and also difficulty with focus, concentration, and short term memory. I'm much more spacey than usual and often will get distracted while having a conversation with someone and forget what we were talking about. My psychiatrist believes these indicate ADD and has prescribed me Ritalin, which I refuse to take because I'm convinced that these problems are side effects of the Lamictal. I've experienced weight loss, but this also may be due to the 200mg Wellbutrin I am also taking.
Although I've experienced more side effects with Lamictal than any other drug, for me I'm willing to continue giving it a try because of its effect on my moods.