I had PND at about 9 months, although largely I think mine was brought on by sleep deprivation, an unrealistic aim to be like Doris ruddy Day and an inability, because I was trying to be perfect, to ask my DH for help, (also exacerbated by the irrational thought that he should just bloody know what to do, even though I'd never really talked to him about how I was finding things).
I found that the act of recognising that I felt awful and that it wasn't lifting and then asking for help, from my DH, and my GP actually helped a huge amount. I also saw a counsellor for about eight sessions and looked at where my feelings of depression and anxiety had come from. It was brilliantly helpful and although I'm struggling with anxiety at the moment, I'm 30 weeks pregnant, I am soooo much better than I was and feeling like I won't end up in the place I was before.
It would probably be worth you seeing your GP, also to rule out anything physical, you could be anemic, have an undiagnosed thyroid prob, both of which can make you feel lethargic and without motivation.
Sorry this has turned into a bit of an essay, I just wanted to say, you might have PND, but that it is more than recoverable from.