Emotions

Firstly, I have to say sorry for keep talking about the same kind of subjects, but hopefully this will be the last time.
I find it difficult to show other people my emotions, well to show people anyway. I panic in situations and just tend to laugh when i cant think of anything else to say. I normally will smile, so that when i am upset, no one knows. I don't like people asking how i am because it makes me think about it more, so i just smile when i am with people. It may seem weird me saying that i don't like talking about my emotions because all i seem to do is write about them on here, but this is just a way of saying things without people talking to me about it face-to-face.
When I am upset, even when I want to talk to people about it, face-to-face I just cant get the fact i am upset over to them because i just tend to keep smiling, so people automatically assume that im not that upset and it doesn't matter.
How can I get my feeling across to people, face-to-face?