Symmetry is good

I'm knitting the Sodera socks for my sister. They are basically Cookie A.'s Hedera socks from Knitty, but knee-length and toe-up. Although I consider myself an advanced beginner-intermediate knitter, I have done very little lace. So these are something new for me. And I've run into a problem. Here're some pictures of the Hedera (left) and Sodera (right):












See how the lace gives two nice, symmetric rows of yarnover holes running up and down each lace panel? The left- and right-leaning decreases gives nice clean lines running up and down the panels opposite each other:
Mine, so far, look like this:

I'm not sure if you can see it that well int his photograph, but not only are the yarnover holes not nice and open, the holes running up the right side (on this photo) of the panels are larger than their partners on the left. Also, although my right-leaning k2togs are nice and neat and make a line, the corresponding ssk are terrible and look really messy. I'm doing the "improved" ssk by slipping as if to knit, slipping as if to purl, and knitting through the back loops.

Basically, my left- and right-leaning decreases don't match at all. Not sure what to do about this. Try going back to the old ssk (slip both as if to knit, knit through back loop)?