Well as you're decreasing the stitches, it will work out. Basically, during the short rowing what you're doing is turning the heel. You'll actually start the short rowing in the middle. So for let's say 20 stitches, you'll knit 12, decrease 1 and slip 1, leaving you at 19, you then start short rowing by turning the work at this point, and purling 5, decrease 1 and slip 1, leaving you with 18, knit back 6, dc1, sl 1, leaving you with 17, etc. and you'll keep increasing the number of stitches you'll either knit or purl. ie, on the previous row, you purled 5, you knit 6, then 7, 8 and so on. does this make sense?