I am so much like you OP. When I get criticism I start to cry, when someone speaks to me in a high tone like in a serious way against me then I start to cry. I cry all the time lol we can't control ourselves as we are too nice and cannot stand harsh circumstances. I would definitely say its to do with our confidence. Like today at sixth form in my Tutor group the teacher asked who wanted to be the form representative and as part of the student council. I put my hand up as well as another girl and guy. Teacher picked me to give my reasons why I am good for the student council. I was in front of the class and all those intimidating eyes made heat come out of my neck and ears and face lol if that makes sense and it felt like I was going red so quick. And no I didn't get picked the guy did, I was gonna cry but he was really nice and confident when he gave his reasons so the class voted for him...so embarrassing. We will both rise one day! Just believe.