I have five week left and still have yet to get my stroller and car seat. I am having a hard time deciding if I need a double stroller or not. I am a single parent and I have 4 year old twins. They are a little bit slower at walking which doesn't bother me but we do go to the mall and fairs and other longer outings. Should I buy a travel system and find a gentle used double stroller or are they old enough to do all this walking without a stroller? I'm just worried one of them is not going to be able to walk for some reason and then I am going to need that stroller.