For the left front, you must be working a wrong side row when you work the 4sts at the front edge and place on a holder. Sounds like you work across the remaining sts, turn and work the right side row, then turn and bind off 2sts at the beginning of the wrong side row and it should be 10sts remaining. From there on you can work the 4 decs on the right side row, say one or two sts in from the neck edge (6sts).
After the last dec the pattern says bind off last stitch? Perhaps it's meant to be "last stitches"? You could check this by seeing how many stitches are bound off at the back shoulder and this may help figure out the number for the front shoulder. Does working the directions (about 11-12 rows) give you a long enough neck opening?