>>2
hits the nail in the head,... By not showing your emotions, you also prevent any help, comfort and understanding that others might provide. And this you need, otherwise you would not have posted here. And it's not absolutely necessary that others understand you perfectly, often the act of opening and speaking freely already helps you a lot. Rather than understanding, I think you should look for someone who is able of listening.

Aside from that issue, there are people who feel there's nothing wrong in their life, but still fall into depression. Depression is really an illness, and sometimes you need professional help. I don't know in which state you're in, but if you feel so helpless that this starts to interfere with your daily life, and causes suicidal thoughts, you would do yourself a favor by seeking professional help.

But that's probably not the case. I suspect like 2 that you put an illusory appearance to others and probably to yourself, which prevents you from seeing and understanding your problem. This you will have to do, even if it's frightening.