Gauge question (lion brand sweater bag)

Hello all. Ok I’m knitting this sweater bag from the lion brand website. The yarn they want us to use has a guage on the label of 14 st and 18 rows rows using 10.5 needles and stockinette stitch. The pattern using this same yarn calls for size 8 needles and a guage of 12 st and 20 rows equaling four inches. How are they expecting me to get fewer stitches per 4 inches using a smaller needle? I actually had to go up to size 13 needles to get the gauge and now its seeming to loose to me. Does this make any sense at all? Any help would be appreciated.
http://cache.lionbrand.com/patterns/60336.html?noImages=

They want you to use a smaller needle for a denser knit because it’s not lined. Did you try smaller needles, like an 8 or 9?

Yeah when I tried smaller needles I got way to many stitches. I bought shetlands chunky because the gauge was only one stitch off of the lion brand chunky. I thought they would be close enough but maybe its the yarn? Im gonna take it back to Michaels tomorrow and see if I can find the lion brand chunky. The shetlands is softer and shinier than the lion brand so hopefully the lion brand will knit to gauge for me.