Monday morning get's my math skills running again:
Let me try to map it out for you:
you have 66 stitches before that row, right
now your pattern does the following:
stitch 1 on your left needle: K 1 = 1 stitch on the right needle
stitch 2 on your left needle: kfb = makes 1 into 2 stitches, total: 3 stitches on your right needle
stitch 3 on your left needle: k1 and after that m1 = makes 2 stitches where there was one. Total: 5 stitches on your right needle.
you have used 3 existing stitches and now you have 5 on your right needle. This section you repeat.
so what you do is k1 kfb k1 m1 k1 kfb k1 m1 (a kfb and a m1 alternating after the k1, really, but the kfb uses up a stitch, the m1 does not) and so on and on and on
That you do until you get to the last 3.
So for 63 stitches you turn groups of 3 stitches into groups of 5 stitches.
that makes 21 repeats (63 : 3 = 21), every repeat being 5 stitches on the right needle. You come out with 105 for this repeat section (21 x 5 = 105).
Now you do k1 (nothing for the next step of kfb for this size) and k2 - so k3 total for this step.
That means you come out with 108.
I hope it helped you?
Having 20 stitches more makes me wonder where you went wrong. Maybe you did not line up end and beginning of the repeat right? 21 repeats and 20 stitches more seam like 20 gaps between repeats that may be an issue? Did you gain one extra stitch between the repeats? Between the m1 and the k1?
you will figure it out, I am sure.