Hi op, I had postnatal depression with my eldest (I have three now). I felt very similarly to you and the evenings were the worst, I kept searching for Mumsnet threads to find people who had felt the same as me. I also didn’t have that rush of love with my eldest (that I now realise is absolutely normal and fine), but I think that made it all worse as I felt this pressure that I should be in a blissful bubble of happiness. Anyway, by the time he was about 3 months old I was getting more sleep but really wasn’t myself and I knew deep down this wasn’t how I should be feeling. Went to GP, who was lovely, v quickly got referred and I was put on a low dose of antidepressants. Honestly couldn’t believe it but within a couple of months I felt totally myself again - well, as much as is possible when you have a baby. But I actually started to enjoy it all and I remember around that time randomly tearing up whilst looking at my son because of how much I loved him; it felt like I’d been so numb up until this point. I stayed on the pills for a few more months but then came off.
to put it into perspective, I didn’t have the same depression with my other two. The newborn stages were just as physically exhausting, and I don’t generally enjoy the newborn stages (except for the daytime when you can watch tv), BUT I wasn’t depressed and it was very different.
anyway, that’s my experience - I would recommend chatting to the GP or midwife (if you haven’t been discharged). No harm in starting a conversation about it. Please also remember that how you feel is so so so common, but don’t minimise it either.
sending lots of solidarity and a reminder that it is SO SO hard having a newborn (especially when it’s your first)…nothing prepares you for it. Also, for further consolation, I never found anything as hard as going from 0-1!