You need two bags, one for labour and one for the post natal ward.
IMO Labour bag should have
something to wear in labour, I wore the same old t-shirt for my four DC,
maternity pads (I wore three at a time one in front, one towards the back and one over the middle),
2 pairs big cheap knickers,
something comfy to wear afterwards, not white and not too hot if you are staying in a vest top and a cardigan is good,
comfy bra,
flip flops for the shower,
big old or cheap dark towel,
hair bobble and brush,
toiletries for you,
bin bag for washing,
nappy, babygro and vest for baby,
camera,
phone,
My hospital provided formula for those who needed it, drinks, and bendy straws.
Hospital bag,
more maternity pads,
rest of your big knickers,
spare pj's for you,
spare clothes for baby,
slippers (slide on are easier if you have to wear lovely stockings like I did)
nappies,
wipes or cotton wool in a tupperware which you can fill with water,
vaseline to stop the first poo sticking everywhere reducing you to tears,
toiletries for you, transfer these from labour bag,
bag for laundry,
cash,
non perishable snacks and any cold drinks you might like,
phone charger,
magazines, books, kindle, a pen,
Leave at home in the carseat,
whatever you want to wear to come home in including underwear,
whatever you want the baby to come home in including a blanket,
Have emergency PJ's and underwear, baby clothes, nappies, maternity and breast pads together somewhere incase you get kept in or use up your supplies.