Sometimes medicines lose their effectiveness over time. Definitely go over tapering off of any drug with your pdoc before you do anything about it. Getting off too rapidly can be very dangerous. Are you bipolar? Also, Lamictal is an anticonvulsant that serves as a mood stabilizer. Mood stabilizers moderate how antidepressants affect us (BPD).
I am on Lamictal but I only take 200mg a day. I tried Welbutrin once, but I just had a headache the whole time I was on it so I had to stop taking it. I am currently on Trazodone. I think the combo I am on now isn't working very well for me, because I feel too sadated and depressed still about half the time. I am sure I will be going through a medication change in the near future. I think Lamictal is use for a mood stabilizer, not exactly sure. Either way be sure that you are also on a mood stabilizer while taking antidepressants. Taking antidepressants alone for people with bipolar disorder can be bad as it can cause rapid cycling or a manic episode. Another thing to remember is that different medications can work differently for each person. I know it can be hard to find the right combo of meds that is right for you. I have went through so many diffrent medications it isn't even funny. Talk to your doctor about going off the Lamictal as you may need to replace it with something else.
Be sure to consult with your pdoc before stopping/cutting back on any medication!