Here's what you need to pay attention to when you buy a diaper bag:
A lightweight, washable (or good) textile.
Oversized sealing container to prevent bottle leaking.
There's a place to put the keys. You don't have to be a special-purpose pocket, but you need to find a place to put your keys, or you'll find your keys locked in the car when you turn everything upside down in an open-air parking lot.
A bag that your husband can carry. You can take the bag when you hold the child.
The mailbox-style diaper straps are easy to slide, and they feel heavy.
You can use the other bags as a diaper bag. Sports kits are also a good choice. A diaper pad and bottle holder that matches a very expensive diaper bag will catch your eye, which is understandable. But it may take months for you to stop using your diaper pads, and you'll remove the bottle holder.