I'd suggest reading some threads in the forums that sound closest to your issues of interest, deciding which discussions sound most like the one you'd like to have, and posting there.

You might also consider posting more than once, emphasizing some issues in one forum and the rest in another. Depression and suicidal ideation are often discussed together, for instance, as are anxiety and nightmares.

In a pinch you could even post the same thread in two different forums and have two different conversations about it.

Hope this helps.