Hi,
I read your post and whilst I myself have not suffered with PND, I have several friends who suffer and are suffering with depression. You need to know that you are not alone and that there are many others out there who feel exactly the same as you do.
Do not feel bad or ashamed for the way you are feeling, you can't help the way you feel. There is help out there for you, i am only surprised that your health visitor has not pointed you in the right direction.
I need to say a few things, because I feel you need someone else's perspective. First of all work is work, it is a means to an end and that is all. You say your employers say you are good at your job. Chances are if they say you are geed then you are good!! Trust me generally employers will not pay you a compliment for no reason. Accept the compliment you are goos at your job.
Are you really overweight, or is the fact that you are feeling down, giving you a poor self image? If it is a case that you want to lose weight, then worry about feeling better in yourself first before you go down that road. None of us are superwoman, despite that some try to make out they are.
As for spending time with your daughter, have you tried taking her to some groups/activities, where you would have a chance to meet some other mums, while she plays. And despite what you feel, your DD loves you just as much as her dad.
I know its probably the last thing you want to do at the moment, but sometimes a little exercise can help boost the happy hormones in your body. Perhaps taking little one for a walk to a local park or something.
However, I do think that you need to rely on support for others. Why not make an appointment with your doctor and demand some help. Admission is the first step to recovery, so you are already on your way.
If you can try and act how you want to feel, I know this may sound daft, but the more you act the way you want to be, eventually the behaviour follows. I have tried this with many of my friends, even had them looking in the mirror each morning and proclaiming " I am a strong, positive and attractive woman" - after a couple of weeks they noticed a difference.
I am not saying that this will work for you, but it is a tactic that has worked for others.
I also found a website, that I think might be beneficial for you, as the founders have suffered from PND, there is also a freephone support line
www.pndsupport.co.uk/index.htm
I hope some of this has helped xx