Don't feel terrible! It IS boring: relentless and repetitive, and the days last FOREVER. Things I'm trying to fill the time:
A big park walk with pram to get DD to sleep and me some exercise, bonus if she stays asleep and I can read a book for half an hour on a bench or in cafe. Dreaming of the day she takes 2-hour pram naps 🙏🏻
Netflix! During long feeds or while DD rolls around on the floor under her activity gym. I use headphones or subtitles if she's napping (which she only does on me). Reading every Mumsnet sleep thread ever.
Slowly making mum friends who also have bad-sleeping, routineless children – more park walks and cake. This is the toughest for me, I've only made 2 friends I like and I hate my antenatal group!
Easy activities like Big Scream cinema, baby massage, storytime. Or taking the baby in the sling to galleries and museums – she looks around then drops off while I have a wander then a scone
Evenings: attempting a bath, book, boob routine that currently takes a couple of hours due to colicky baby but at least fills the time and gives me something to do to feel vaguely in control of a routine refusenik, sleep averse baby!
It does get more fun when they start smiling and coping and rolling so you can chit-chat or stick them in a bouncer to watch you shower/make toast/do laundry.