Need decrease help at each end of purl rows for sleeve

[normiek]

My pattern calls for decreasing 1 st at each end of every other row for the shaping of the sleeves. For whatever reason, I decided to make the decreases on the purl rows. So, I would purl 3 sts, then I purled 2tog. Then I would continue to purl to the end of the row until there were 5 stitches left on needle, then I purled 2tog, and then purled the remaining 3 stitches. When I look at it from the RS, the stitches do not look the same on either edge. On the left edge, the decreases make this nice slant to the right, but on the right edge, it looks weird. So, I thought I would just use that sleeve to be the left sleeve, so the nice slant would be at the front of the sweater, and I would somehow create the other sleeve to be the opposite, so that it would have the nice slant on the right edge of the RS, but I don't know how to do that.
I hope this is making sense. How can I get the stitches on both edges of the sleeve to look the same, i.e. slant towards each other? If I can do that, then I will correct the sleeve I already finished.