I'm new to knitting, completed a few simple projects, but now I'm trying to make a sweater for my daughter. I need it to be slightly bigger around the chest than the largest size on the pattern. The four sizes on the pattern say the finished size is 18", 20", 22", and 24" around the chest. I need 26" around the chest. The woman at the yarn store told me to use a slightly thicker yarn (worsted weight instead of DK), and slightly bigger needles (US8 instead of US6). When I make my swatch, I get 35 stiches to 4" instead of 22 stiches to 4" like the pattern says. How do I figure out which of the four sizes on the pattern to follow in order to make my project the size I need?