Anger is an emotion, and the Lamictal your taking should be addressing that. Maybe its not working and an adjustment in meds might be needed. You should talk to your Dr about this. I could be wrong, but I don't however see it being hypomania.

I use to have serious problems with anger and controlling it. Since i started taking a low dose risperidone, my anger has disappeared, and i don't get triggered anymore.

Good luck