Mistake 1 - when dividing in half, I forgot there were two extra stitches at the end... so I divided at a point 1 stitch off to the side, which made one strap of the front 2 stitches extra (I added decreases to offset them).
Mistake 2 - I missed a decrease on that same side on one of the right-side-rows. (Threw in an extra decrease for it as well).
Mistake 3 - I swore up and down and right-side wrong-side ... and even ripped back my first 8 inches after the divide once already... that the v neck was starting too soon. (it wasn't... I wasn't thinking about the added collar that needs to be added later. (head-smack) I'm living with it ANYWAY.
At least I think I am. I may not have the right number of stitches on the front to match the number of stitches on the back... but if I can fudge that bit as well? We're going with it. It's still going to be a wearable sweater and it's not like anyone is going to be holding the picture from the pattern magazine up next to me while I'm wearing it.