Dearfoams Women's Rebecca Slipper, 13-14

I like this brand and style and buy them often, but something is different about these velour ones. They are so loose that my heel slips out about every fourth step as I walk. I wear a size 7, and these are 7-8. Don't know if that is the problem. Whatever, the slippage is very inconvenient and makes it hard to walk. Otherwise, the slippers are soft, spongy, and comfortable.