You start by knitting one half of the sock then the other. These two are joined when knitting and shaping the toe. Casting off, then sewing up a seam to close the top of the sock for the toes and then all the way down the sole of the foot and back of the heel.
I am sure you can make the slipperette longer in the centre of the pattern as there is no increasing there.

Also if you want the slipperette a bit more secure, at the end/start of every row is a k2 (depending on what half you are making) so you can knit in shirring elastic right along the edge. Or once made up, weave a fine ribbon.