CokeMachine I could have written your post at 6 weeks, it was a really shit time. Exhaustion has well and truly set in, the novelty/adrenalin/whatever of this being new has worn off, and it's just a drudge. I hated it. I would have given anything to turn back the clock and not have had a baby. I think expectations have a lot to do with it, especially because a lot of people said 'the first 6 weeks are hard then it gets better', which just made it worse as for me 7-8 weeks was my real low point and I was looking round thinking 'everybody said it would get better'.
DD had silent reflux, which meant lots of crying, and I had mild PND (do get both of these checked out), which made everything worse, and yes, I absolutely regretted having a baby. I remember this was around the time DH and I both said we felt black inside.
But it changes! It does! Around 8 weeks your DD will start to smile at you, and do things, and from around 3 months you will start to see a personality budding. My DD is 9 months now and I adore her.
This is going against the mn grain a bit here, but once DD had her reflux meds sorted, both she and I were much better off with a fairly strict routine. Not all babies just drift off to sleep when they're tired, not all babies feed well on demand, some babies need to be carried around all the time, others sometimes just want to be put down. I went fairly GF-ish at about 6 weeks and it worked really well for us. I'm not saying this is the right thing to do for you, but I am saying that don't be afraid of trying new things if things are not working out for you, even if it is something that you feel is not quite the current thinking.
I had to go back to work at 6 months for financial reasons, so we're now all settled into our routine, but I miss her! I would have come back at 6 weeks if someone had offered me the opportunity, but it would have been the wrong thing to do, as I don't think I would have 'come through' it, rather run away from it, IYSWIM. I don't mean you're trying to run away, I am just reflecting on my own experience. Work is a walk in the park compared to all day alone with a baby, but I think if I had come back at 6 weeks, I would never have fully trusted myself that I could handle the motherhood thing.
Anyway, I can totally sympathise, I felt just like that, and it does get better!
D