Vertical Buttonhole help

I’m a beginner knitter and I’m a little confused by directions in a pattern that was supposed to be “Easy”. I’m working 19 stitches and the instructions for making the buttonhole state: “Work across 11 sts in pat, bind off the 10th st (9 sts will be on the right needle after bind-off); cont across rem 9 sts in pat.” Eventually I’m supposed work with 2 balls for separate sides of the opeining for 1½". My problem is that I work the 11 stitches in the pattern so I have the 11 sts on my right needle and 8 stitches on my left. Then I bind off (I slip my left needle into the 10th stitch & bring the 11th st into it which remains on my right needle.) I now have 10 stitches on my right needle not the 9 I’m supposed to and I still have 8 on the left. How is it that the pattern says I’m supposed to have 9 sts per needle? What am I doing wrong! :thinking:

After you bind off the stitch, the one that’s left is technically part of the second set of nine, I believe. So you’ll have 9, a gap where you bound off, and 9 more. Is that the way it looks? Then you’ll work each side of the gap separately for the buttonhole and join the sides again when it’s done.