I researched the crap out of PND after I had DS (7 months next week). The symptoms didn't seem to fit me. I would panic when he started to cry at night, this feeling of an elephant on my chest. I would stand over his crib and cry, wondering WTH I had done. To myself. To DH. I briefly considered adoption, but knew there was no way that DH's family would let that slide. I would google everything, trying to figure it all out (am I feeding him too much, not enough, how much weight should he gain, am I holding him too little, too much, am I not helping his sleep associations, when will he sleep better, is sleeping on me bad for his naps... etc etc). My nurse (equivalent of HV) realised I had anxiety with a touch of depression. I felt so out of control that forgetting to put the bin out on bin day had me in tears because I "failed".
I fought it for 6 weeks. I promised my OB that if I didn't feel better by then that I would at least try sertraline (zoloft). The first week is rough because anxiety tends to get worse so I had a quick acting medication to help with the rough patches. It took maybe 2 weeks, it can take 4 or so, but that's when I felt like myself again, more able to cope. I still had panicky moments (work related), but it's been a while now and I feel a world of difference!
Like you, I was numb the majority of the time, but then I would have an anxiety attack over the stupidest things (or him crying). We had baby photos taken for Christmas. I look back now and feel bad how uninterested I was in them. I wanted the photos, I knew I SHOULD want the photos, his first Christmas and all that, but I wasn't interested in posing him, or wanting this pic or that pic. MIL did most of it.
I don't know where I'd be without the support system. I'm not sure part of mine was due to going into labour 3 weeks early (water broke) and just not thinking it was "time" but now I'm glad I did those photos, I'm glad I saved the stuff from birth until I was feeling better (to make a shadow box). I was really hoping that I'd feel like it one day (and have the time frankly!) and I will and I feel excited about doing it.
As people always said to me you wouldn't suffer with a headache, you'd take something to help it. Don't feel like you need to suffer through. If medication doesn't work, you'll have other options too. Don't be afraid to talk about it. We'll help you through it (and I suggest you move this to relationships or a baby related thread.