I'm not exactly sure what your problem is, but I know that I knit someone a garter stitch scarf in Caron Simply Soft, which seems to me to be a bit on the lighter side of worsted weight. I knit it with size 13s (I know!!!) cuz I thought it looked cool but stretched out OUTRAGEOUSLY...
"An excellent woman, who can find? She is far more precious than jewels . . . She seeks wool and flax, and works with willing hands." - Proverbs 31:10;13
I'm a knitter for Jesus!