I have OCD but I've haven't had depression or PND, but me having OCD doesn't really make a difference to how I read what you've written.
I'm only giving you my opinion and I'm not an expert in any way, shape or form, but the expectations you have of how 'things should be' seem to be extraordinarily high.
Which could be what your doctor was trying to say, that if things aren't exactly as you think they should be, then all is not lost and it doesn't mean you're a failure.
If you were feeling more on an even keel you'd be able to rationalise those things that don't work out as you'd like as just a blip in the day and nothing more. Recalling that it's just not possible to have a perfect day and everything go as you think it should do, and it doesn't mean you're a doing it 'wrong' or you've gone about looking after your DD in a way that's detrimental to her.
Accept you've had a life changing event and ease yourself into the very high expectations you might have of how it should be done. In general society, the high expectations of parents are only guidelines because none of us have the recipe of what makes a good parent, we're all just making it up as we go along...well...most of us 
What I'm saying in a very round about the houses way is try and relax, (that bit is from my OCD) it's OK to enjoy your DD and everything turn out alright 