Depends what you mean by anger. An agitated mixed state is part of bipolar where the person has the down quality of depression but the speeded up quality of mania so they seem angry at the world. It also depends whether this occured because of the medication not working or the medication itself is worsening it. Speak to your psychiatrist about it.
I can't tell you to up your meds. I have a severe anger issue as well, I'm about as patient as a wasp (that's probably a stupid example, but it's early), and I'm irritated regardless if I'm up or down. It's aggravating, I know. Talk to your Dr about upping the meds. But for me, therapy has worked a bit. If I'm having a really bad day, she'll schedule me in that day. But pdoc put me on Abilify (combined with all my other stuff) and that helped a lot in taking the anger down a few notches, if you want to consider that. I don't really know how well the Lamotrigene is working for you, but definitely talk to your DR.