Have a 3 and 1 yr old and need a new changing bag as my old babymel one is on its last legs. I want one i can use as a backpack ideally, and liked the look of the babymule as looks like it could convert into a messenger bag if i have the youngest in a carrier. But its expensive and review online said its better as a shoulder bag and quite cumbersome as a rucksack (probably what I'd mostly use it as). Any advice??