Okay...I experience a lot of what you go through. Irritability is really hard to manage, b/c I feel so angry, and it does seem to come out of nowhere and it's extremely hard to control--it actually feels impossible to control.
I think though you've got the right ideas. Leave the room; calming activities, like colouring is perfect!
Cycling is the pitts--that is what I deal with. I'm on Lamictal too, and my pdoc is watching me b/c apparently Lamictal could increase cycling too, so that might be something you could ask your pdoc about? Do you keep a mood chart? You can get some off the internet--but they are really helpful to see how many times your mood is changing in a day, if you took all your meds that day. Patterns of episodes etc.
I have a feeling that for me and my cycling, it probably would take a lot of meds to get it under control, but I'm just not willing to go on a lot, so I'm just trying to deal. In my bipolar support group, basically we would start our sessions with "where is your mood at today" (low-high) and then "what can you do to bring yourself down/up to stable?" I ask myself that when I feel a change or any extreme of the mood spectrum..."What can I do to help shift things a bit?" It's very effective for me.
I can elaborate more on this if you need me to. I'm beat, so I have to go to bed now, but I am thinking of you and you are definitely not alone. ((((hugs))))
Bipolar II, Anxiety/Panic Disorder
Clonazepam .5mg as needed, Trazodone 50mg/day & Lamictal 200 mg/day