I was taking Lamictal by itself for depression at 400mg and it worked well, EXCEPT for anxiety....
The only problem is/was, it absolutely destroyed my memory in certain ways. Many many tip of tongue moments, and I absolutely could not learn new directions. It was really odd.
*Edit: your story of the generic not working scares me. I have that experience with Prozac and Effexor. Going from working great to not working at all (generic) OR one generic working, then getting switched to another and it not working. Very frustrating.