How to Prevent heel slippage in running shoes
This video demonstrates that just because a shoe feels loose doesn't mean it's the wrong fit. Many shoes have a back eyelet that rarely gets used, but if you put your laces through it before tightening, it will raise the fabric of the shoe to give more support to the heel. If your shoe doesn't have this extra eyelet, you can create false eyelets by creating loops with your laces on the top two eyelets of the shoe, then lacing them through those fake eyelets before tightening. Both of these methods should create a better fit and prevent your heel from slipping.