craftgrrl | Double Crochet increasing and decreasing

Okay, so I'm working on my second (and third) crochet projects. One of my co-workers is having twins, so i'm making baby blankets. I was talking to my mom about them, and she told me how to make it wavy. So what i have been doing is double crochet 9, then do 3 double crochet stitches in one stitch (does that make sense?), then crochet 9 and then skip a stitch. However, I've discovered that doing it this way is making the blanket wider and wider. My question is, should i be skipping two stitches if i'm doing 3 stitches in one stitch? Or am i doing this completely wrong? My mom had to explain this to me on the phone, cause i'm at school right now and 500 miles away, so its very possible that i heard wrong or she misspoke or something. Any help with this would be very very much appreciated.

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