Lamictal is a good drug. I was diagnosed with bipolar 1 at 18-years-old and started taking it. Still taking it to this day at age 22, and I haven't experienced any negative side effects. The most adverse side effect of this stuff is some sort of fatal rash.. but it is rare.
What dosage are you starting at? I suggest that after you begin taking it, you fill out a daily "mood chart" for the next month. Maybe your psydoc has one. It's simple, just rate your overall mood at the end of each day between -10 and +10 (of course the negative numbers are depressed, zero is neutral, and positives are happy and/or manic). This can show you whether or not the drug is stabilizing you or making you worse.