My DS1 was a very unsettled baby and believed sleep was for the weak. I spent the first 8 - 10 months of his life crying a lot, walking out and leaving DS with DH for a few hours so I could have some space (telling DH I wasn't coming back, but of course I always did), convinced I'd ruined my life, ruined my husband's life and wishing there was some way to 'send DS back'. In retrospect, after discussing recently with my midwife when pregnant with DS2, I believe I had PND.
Once I went back to work part-time when DS1 was around 7 months, things started to get better as I had some space (I don't have family nearby, nor many friends, so once DH went back to work after paternity leave, I didn't get a break unless he was home - as I'm sure is the same for a lot of folk). As DS developed and learnt to sit, crawl, stand and walk, things got progressively more fun. Hard work, yes, but much more interesting. He's now 22 months and DS2 is 5 weeks. It's hard work in a different way (today has been the day from hell, but that's another story!) but DS2 is a much more settled baby (actually sleeps - good god, I had no idea some babies actually slept) and DS1 is so funny as he learns to talk and develops.
I too had images of happy times on maternity leave when pregnant with DS1 and was horrified that it was just a time of relentless misery. With DS2 I can see how it could be a time of relative relaxation and enjoyment (if I only had the one to deal with
). I do think it's just down to the 'type' of baby you get. Some people are lucky and have 'easy' babies, some of us, not so much!
I wouldn't say it gets easier, but it gets a lot more fun and fascinating and as you get more sleep, things are more manageable.
I hope you start to see this side of things soon as your DD grows.