Becky why don't you ring your health visitor in the morning? She could come over and talk things through maybe and then you would be clearer? I know people moan about health visitors but I think your health visitor may be the person who would help here.
I think sleep deprivation is a major, major nightmare. (It leaves me really really irritable and unreasonable, rather than weepy or sad, but still enough to make me feel there is something wrong with me.) It sounds as though you are really not getting enough sleep and that has a snowball effect. Can anyone/ a group of people take Toby off your hands for a long stretch of the day regularly for a couple of weeks so you can just try and relax for a bit even if not sleep?
I too have been wishing for this stage to pass and for Hedy to be older and easier. I forgot what a luxury it is to be able to just go for a swim or something! Or to see a film, move freely around without a babe in my arms all the time. I have also been mourning the old family unit, which was just the three of us. I'm sure all these thoughts are not abnormal. Having a dependent newborn is extremely frustrating.
Do you normally get the winter blues? I am sure the weather isn't helping either!
I don't know about pnd but I have had a bout of normal depression in the past and the 'not feeling happy at all about anything' is what it was like. I felt like a stanger to myself, or as if everything had turned black and white, with all the colour drained away. I used to wonder how other people had the energy to DO anything at all because I didn't have ANY! It was not like just feeling a bit stressed or overwhelmed, it was a total lack of energy or joy. If that is how you feel then maybe it could be a bit of depression?
I really feel for you and I hope you get some sleep, and to talk to someone helpful about how you feel.
Big hug! If I lived near you I would stick Hedy in the sling, your Toby in your pram and walk the pair of them around all afternoon tomorrow so you could rest. But it will have to be a cyber hug instead sorry!