The decrease sts are going to change as you work the rows. The first decrease is a knit and purl st, the next time it's 2 knit sts. Do a ssk (slip the sts knitwise and knit together through the back loop) for the k and p decrease and a knit 2 together for the others. Put the decreases all on the right side rows.
Every time you do a decrease row, start the decrease 8 sts (for the smaller sizes) from the end of the row. Decrease the first time (row 1) and then decrease on row 5, row 9, row 13, row 17, and row 21. These decreases are going to interrupt the knit 2 purl 1 pattern but if you look at your sts on this edge and knit the Vs and purl the bumps or loops, your pattern will look fine.