When our 2nd was born, our older one was just 2. I found that a large open top purse worked best for me as I had quick access & I shopped at Sam Moon so if a sippy cup leaked, it wasn't the end of hte world. My diaper bags were too much of a pain to get into if I was holding the baby or pushing a cart. I did keep diapers for each kid in ziplocks, along with a spare outfit in seperate bags - handy so that you have somewhere to put the dirty clothes or diapers. Another bag kept pacifiers & snacks. I do keep a bag in my trunk with clothes, diapers, wipes, medicine for emergencies (just don't forget to update it with diaper size/seasonal clothes) and that let me only carry what I needed. I've found that I use way less while I'm out than I ever thought I would. Hope that helps!