if it is depression, you hiding it/allowing you to refuse to treat it for fear of discovery may actually fuel the situation not help it.
I'm not saying shout it from the roof tops, but IF you are depressed, either with antenatal depression or 'straight forward' clinical depression, it really is vital that you ARE given the right support.
depression is an illness, like Asthma, and it can be life threatening too.
Try to analyse what it is you are worried about when you find yourself stressed, ask yourself (out loud if it helps) what is the worst that can happen? challenge destructive thoughts at each and every opportunity, try to see them for what they really are and not what your fears may be making them out to be.
Try and specifically do things to cheer yourself up, see how you feel afterwards, if you are still flat, then please, pop along to the GP for a chat and see if they can help you.
You don't need to be in despair, please let others help. MH issues are not the life sentence they were. 1 in 3 people get depression, it's very common, but can be controlled and treated.
Keep posting, keep talking and bounce ideas etc off us if it helps you?