How come kids can scream so loud?

Where does it come from? Such a small person, with a scream that makes your ears bleed! Daughter had a strop on this morning, why.. I have no idea, I obviously said no to something. The screaming got so bad I just broke down and cried. I've not cried like that in ages, the uncontrolable kind, where you can hardly catch your breath. I hate being like that, I need to be strong, because she must be confused that her dads not here and frustrated that she can't ask why. I spoke to another of my 'friends I've made online', he listened to me rant and gave me some good advice, for which I'm grateful.
I wonder sometimes if I'm cut out for being a parent, I wonder if every parent thinks that... even those one's that bore you to death talking about their kids. I wonder if I was really ready for the responsibility. Ok I know I'm in my 30's but I always said I'd never have kids because I'm too selfish. I wonder if hubby talked me into it, and I just went along with it because he really wanted a child. Our little one wasn't entirely planned, I knew that eventually, maybe we'd have a child, but it happened unexpectedly. People always say to me, when I turn into stressed mum, "Oh but I bet you wouldn't change it?"... no actually I would, I'd have given myself another 5 or so years, until hubby was out of the army! I do miss having a life of my own.