My life is affected by this but it is not uncontrollable. I have moments where I behave recklessly but thus far I haven't done any serious damage to anyone else's property (though my own computer and desk are quite blackened

I refuse to quit setting things on fire. While it may be unusual I do not think it is altogether unhealthy. It helps me release negative emotions and makes me happy. If I could learn ways to control the impulse than I don't see anything wrong with it.
Do you think a therapist would see my side and assist me as I need?
Is the impulsiveness going to get worse over time if I don't start trying to learn to better cope with it now?