Sorry to hear you're having such a bad time of things - do take something from the fact that you've gone through this before and came through it - you're obviously a strong lady and at least this time you recognised the symptoms and have got help straight away x
Counselling might help you work out in your mind what makes you feel unhappy - although I did suffer from depression once and had some time off work - and I still don't know what triggered it, I just know I felt like hiding away and couldn't face the world, suddenly life and simple things became too hard if that makes sense (I think it will). It could be as "simple" as the fact that you've had major changes in your life and you feel over-whelmed, whether your new baby, previous MC's, changes to your relationship, demands on you and so on - don't under-estimate ever how hard one of these things can be let alone all of them together, if you've carried this in your mind for a long time then talking might help to really focus on how you feel.
I apologise now if you read this and feel I have simplified your situation, I promise you I don't mean to do that, situations like this are so complex and very real.
Remember we're all here to lend an ear. even if you just need to rant xxx