I know its a hard thing to do, but try not to put so much emphasis on other people's problems .. i just mean don't compare yourself to others because it is in a way minimizing what you are going through. I know I often feel guilty about talking to someone if i know that they have "more issues" than i do ... but the truth is, comparing yourself to others is like comparing apples and oranges.
I also hear what you are saying about not being able to pin-point exactly what you are depressed about, or what happens to be making you upset from one moment to another ... but that is because you are so overwhelmed you don't even know how to put the pieces together. But if you were to imagine someone asking you all the right questions, someone that knew you knew what was wrong deep down, and forced those issues to surface, i bet a simple yes or no answer would quite quickly show you that no, things arent okay right now. And that really is okay, no one expects you (or anyone) to be perfect, and have their life in order ... but, just know that you are NOT wasting anyone's time, and you have to believe that you do have amazing strength and courage. We are all here to help you get through this, just try taking things one step at a time.
I hope this helped even just a little bit....
(((((((((((wanting)))))))))))