Help! knitting

[bruffin]

I am making a jumper fairly simple quidditch jumper which is a k2p2 straight up. The original pattern was dk 120 stitches but chose to knit in super chunky and reduced it down to 90 stitches. Also dd is a curvy size 6/8 but don't mind it being loose.
I am just at the shaping part. Do I reduced all shaping by 3/4 ie only leave 9 stiches on holder instead for 12 for the neck.
or here
"Change back to CC and cast off 3 sts at the beg of the next 2 rows, then 2 sts at the beg of the following 2 rows" do I cast off 2 st for both rows or leave this bit the same and make adjustments elsewhere?

I would do the whole thing 3/4, where you can. However as you are only talking about a couple of stitches here I don't think it will make any difference!!!
K

The link does not work, but if you are doing the whole thing in a 2x2 rib it will be stretchy both ways. I think 9 sts for the back might be a bit tight, you want her to be able to get her head through it, so I think I would probably make adjustments elsewhere.

Thanks , yes thats the link. I am up to tge neck shaping now and will keep it at 12. I think. I cut down som of the shaping on the arm.
Im having to do it in secret . I doubt she will wear it too much. Just fir fancy dress or comicon

Not that sure now I've seen the pattern. The 12 sts are only the ones you reserve for the front neck, in all she has 138 (?) round the neck which obviously you have to reduce by 1/3. So 9 sts for the front might not be the worst idea.