Unable to express anger. So automatic.

Hello, I'm little short tempered I usually get angry/irrtated/frustrated and these emotions ine can clearly see on face ! But rather than expressing I keep it inside, I control alot, like seriously I control alot of anger inside me sometimes when I can't or won't express it I feel like throwing stuffs or feel like shouting loudly!! But I do neither of these.. !!! Instead of that I press my teeths tightly for few seconds or cry or fist my palms really tight...I feel if I Express my anger i might hurt the person being rude/ aggressive (this includes my family, friends basicallyclose ones). Because I have experienced that right after being rude I feel really really bad and I start blaming myself for everything. And my friends think I dont have anger issues! But the thing is I have instead of showing up I keep inside my head and it doesn't feel good. And everyone say I'm always always smiling without any reason... somewhere its true I don't I do that but why!! It's so automatic...