Check how you do YOs, they just add a stitch and don't use one. Wrap the yarn around the needle, not wrap and knit 1. So when you do Row 1 - K2tog, K6, yo, K1, yo, K6, sl 1, K1, psso; - you'll have a single stitch between the YOs, then 6 sts then the decrease.
If you do a K1 after the YOs, you use up a stitch and don't have enough to do the right number of repeats.
sue- knitting heretic