For example, my feet are the same length but the arch of my left foot is flat while I have a high arch on the right. So if I get a pair of shoes, the right shoe always seems to fall off when I get something that fits the left. If I get a shoe that fits the right foot, it;s always too small for the left. How do you get around that, especially with ordering online? Or are you limited to only local stores in a case like that?