I am a VERY emotional person, and i am just wondering why?

As far as i can remember i have been an emotional person. But in the last 5 or so years it has really intensified. In just about everything i do i want to cry. I will watch a move/show on tv and something on it will be sad or really happy and i start to cry. same with songs. I just dont understand. People tell me it's because I have a big heart. I kinda get why i cry when i see something that saddens me, but i dont entirely get why i cry when someone in a movie/show is happy. ex: I am watching tv and someone finds out they are going to have a baby and i see them happy about it, it makes me cry. maybe its because im afraid im not going to have kids, i dont know. Maybe im crazy. I sometimes feel crazy sometimes because of this problem. If this is some kind of disorder, is there any help for it, or cure. If someone can please shed some light on this problem for me it would be appericated. Only serious answers ONLY!!