Hey OP, just wanted to tell you about my experience of PND and post natal anxiety: basically I become totally fixated on the idea of getting DS's daytime sleep right and obsessed to the point of mania about his naps and getting him into a nap routine to the point where I made myself very ill with anxiety and then depression.
I used to spend whole days working out when DS would need to sleep and wouldn't leave the house if a nap was due (every 2 hours), would cancel outings etc to fit in with his need for sleep. Until the age of 7mo he too would only have 45 mins sleep every 2 hours or so, and I thought I was getting something terribly wrong cos he wouldn't have a big long sleep in the afternoon like all the books Gina Ford said he should. No one told me this was utter bollocks and i drove myself literally almost insane worrying about it. I too suffered from insomnia and couldnt sleep even when DS was asleep, as I couldnt turn off my brain from worrying about how little sleep I was getting. I think in my case this stemmed from the fact that for the first 6 weeks of DS's life he just would not sleep at all from about midnight until 6am so I was up all night every night and i became terrified about things going back to being like that.
If any of this rings true to you, please go and talk to your HV and get some help....I got some brilliant CBT counselling which really helped with the anxiety and a very frank talk with the HV also helped. She could reassure me that the fucking awful nights I had with DS in the early weeks were newborn behaviour and it was never going to be that bad again. He didnt start sleeping through till he was 6mo but she was right: it was never as bad as those early weeks again. we have of course had bad phases with teething and odd nights where I have been up a couple of times with him. but it's not like looking after a newborn which i couldnt fucking stand It was cope-able.
DS is now 11mo and I am still battling with my anxiety about his daytime sleeping on a daily basis and do to some extent feel like I have to use my CBT techniques daily to keep myself calm. Things have just gotten easier as he has spaced his naps out a bit more and started taking longer Gina-Ford-Style naps in the afternoon of his own accord (this happened at around7-8 months and I did NOTHING to make it happen, i think it's a developmental thing and they just do it on their own?....he just started being able to stay awake longer in between each nap and therefore dropped down to just two naps per day: one in the morning at around 0930 and one after lunch at around 1330). I do still plan our days around his naps to be honest with you: I think I am always going to be like that. But at least it's easier now there's just 2 of them to worry about!
Unlike most parents, can't bloody wait for the day when DS has no naps at all! Just not having to deal with my anxiety over this (even though I have been treated and I know its daft, it still lingers on...) will be such a relief.
Anyway, sorry for rambling....its just a lot of things in your ost struck a chord with me. PND comes in all sorts of funny shapes and sizes, and lots of women have post natal anxiety which is a bit different from depression but actually probably a bit easier to treat. Please speak to your GP or HV and be honest about how you are feeling and thinking about things every day. I hope they can refer you for some help.