Pattern says:"Inc 1 st each side every RS row 1 time, every 4th row 3 times, every 6th row 2 times, then every 4th row 1 time". I start with 39 sts, end with 53 sts so I understand I'm increasing 2 sts on 7 rows but which rows?
Thanks for the question and visit. You need a row counter or pencil and paper to keep track of rows for this increase. The increase begins on the upcoming right side row, and then every 4th after the 1st decrease x3, then every 6th after previous dec 2 times, then every 4th row after previous dec 1 times. I am using instruction you wrote and break it down into steps here to make it easier to understand where to do increases;
1. Make 1 stitch-increase on each side of the next right side row. (total of 2 sts increase)
2.*Then knit 3 more rows and do 1 stitch-increase on each side of the next row (which is the 4th row after previous inc row). Repeat from * 2 more times. (total of 6 sts for this round of increase)
3. **Knit 5 more rows and then do an increase on each side on the next row (6th row after previous inc). Then repeat from ** once more. (total of 4 sts inc for this rnd)
4. Knit 3 more row and do inc on each side on the next row which is (4th row). total of 2 sts inc.
I hope my explanation helps. Good luck on your project.