Without a stroller basket, every item has to be carried by an adult. That makes the bag's weight and access more important than its advertised capacity. Begin with a short outing's actual supplies and decide what genuinely needs to come.
Try a backpack or another style that can be carried securely and comfortably for your route. Check straps with a realistic load, not only with an empty display bag. If you use a baby carrier, follow its instructions and make sure the bag does not interfere with the carrier's fit, your balance or the child's position. Do not attach a bag to a carrier unless the manufacturer explicitly permits that arrangement.
Keep the common items near the opening
Put changing supplies and the current spare outfit where you can find them without unpacking everything. Use a separate place for adult keys and phone. A few clear compartments are more useful than many small pockets whose contents you cannot remember.
Consider how you will reach items during the outing. Plan to stop somewhere suitable rather than trying to manage an open bag while crossing a street or carrying a child awkwardly. The bag should support safe handling, not encourage you to do several incompatible tasks at once.
Choose materials and a lining you can clean as directed. Used clothing needs a separate suitable container, and any food or milk must follow its actual storage requirements. An insulated section does not replace an appropriate temperature plan.
Let the route limit the load
A nearby walk may need less than an afternoon with several transfers. Remove unused extras after reviewing a few outings, but keep the essentials for the child's current needs. If the load is repeatedly uncomfortable, shorten the route or change the transport plan rather than assuming a larger bag will solve it.
When you return, empty used items and restock before the next trip. A bag that is ready but light enough to carry can make a short outing simpler. Its value lies in how it works on your shoulders and in your hands, not in how much can theoretically fit inside.