Hello, and congrats on your pregnancy!
I have a LV diaper bag in Khaki, and am attaching pics of the front, back, unfolded so u can see the attached change mat, and the inside of the bag.
Here's what I usually have in them:
up to 8 diapers
diaper sacks for disposing of soiled diapers
baby wipes
barrier cream (small tube)
2 change of clothing for baby
bib/washers
spare socks and a beanie for when it gets cold
The compartments in the back of the bag:
wallet
key pouch
car keys
small agenda
That said, I recently purchased a balenciaga weekender to use as a diaper bag for those days when I need to carry a lot more stuff (when I'm out and about for longer periods, or travelling). I find that I need more space to carry a spare change of clothing for myself (for accidental baby spews and mishaps), thermos and insulated carrier for heating and storing EBM, and sometimes my electric breastpump so I can express breastmilk (sorry if this is TMI!!) if I'm out for ages.
I love my LV diaper bag, and have had many nice comments on it, but the buckles drives me insane sometimes! Hopefully they will design a new diaper bag with more functional fasteners!
Have fun picking a diaper bag!