Don't worry so much about the row gauge, you need to match the stitch gauge. Also, cast on extra stitches so you don't use the end sts in measuring. They're a different size than the middle ones and curl under and can give you the wrong measurement. So cast on about 25 sts and knit about 3-4", then measure. It's also a good idea to wash and/or block your swatch as some yarns relax and stretch or shrink up a little.