You know you're really stressed when you talk yourself out of having a massive rant on your LJ because it will require too much time and energy. Worse still, you manage to talk yourself out of being angry because that also expends power you can't afford to waste. You might argue that you're just being calm, rational and zen, but you know that you're incapable of being calm, rational and zen when you're angry. When you lose your temper, you're one of two things: totally pissed or homicidal.
Another sign that you're really stressed is this strange quirk you've picked up of writing in the second person. Usually, when you're upset, you refer to yourself in the third person. You wonder briefly if you might be having some kind of breakdown then dismiss the idea because you haven't had enough time to have a breakdown.