You begin with 75 sts, then on the first dec row - K6 ,*sl1, K2tog, psso, K12, rep from * (this is 15 sts, repeat 4 times) end K9. The 6 and 9 are also 15 sts, so with the 15x4 that uses up all 75 and leaves you with 67 sts.
Next dec row - K5, *sl1, K2tog, psso, K10, rep from *(13 sts 4 times) , end K8. But 13x4 = 52 plus 13 uses 65, which ain't 67. So there's your 2 sts. I think if you just keep following the pattern so the sl, k2tog, psso are stacked over each other, it should work out. You may have to count them out to make them lined up, but maybe that's just an error in that row only.
Did you check for corrections to the pattern? They can often be found online. If you explain what 'KDM' is maybe we can find it on ravelry and see if others ran into the same problem