How to bind off every other row?

Hi
I'm trying to understand how to shape the armholes in the front and back of a sweater. My pattern says:
On every other row bind off 2x2 sts and 3x1st at both ends for the armholes.

What I did:
Row1 (RS): bind off 2 sts. Knit to the end of row. Because you cannot bind off stitches at the end of a row, I did it at the beginning of the wrong side row :
Row2 (WS): bind off 2 sts. Purl to the end of the row.

Row3 (RS): bind off 2 sts. Knit to the end of row.
Row4(WS): bind off 2 sts. Purl to the end of the row.
The I did the same for the 3x1 st at both ends of the armhole.

My question is: is this binding off on EVERY OTHER ROW?

I hope I'm clear enough for you to understand my question.
Kind regards
Maria