Originally Posted by salmonmac
Yes, definitely count the slip knot as a cast on.
I'm not so sure why the first and last rows are shorter. It's possible that your cast on and bind off are much tighter than the other rows. You could try a looser cast on (see the Free Videos tab at the top of this page, cast on, for an alternative cast on) and for the bind off, try using a size or two larger needle to bind off.
Okay, thanks a lot. I'll try and see what happens.