If you have low volume flat feet like mine, the problem you describe will be fixed by buying shoes or boots that fit the volume of your foot. My feet across the ball are wide, and at the heel, narrow. I recently found Keen footwear to offer the best fit for me. A very basic rule of thumb is that if the shoe doesn't look like your foot in length, width, shape, and volume, it probably won't be a good fit unless you go up in size.