After much thought - and careful measuring - I think the pattern might have a mistake and that's the cause of all the extra width, which actually totals in about 4 extra inches! Someone please correct me if I'm wrong because the other knitters on ravelry didn't seem to encounter any problems, at least they didn't mention any in their project notes.
So the gauge for the pattern is 20 sts = 4 inches and 28 rows= 4 inches. My gauge was off, but it was 20 sts / 26 rows. So that's roughly 5 sts per inch. The pattern also states that the finished measurements are 18" for bust and 14" for waist. If so, then 5 sts x 18" = 90 sts. That seems about right since the number of cast on stitches is 89. But here's where I'm confused... If 5 sts x 14" = 70 sts, then why does the pattern say to decrease only to 79 sts? Shouldn't I decrease to about 69 sts in order to get 14" for the finished garment? When I knit this top I followed the directions and decreased to 79 sts but then the finished garment measured 16". So again, if my math is correct, 5 sts x 16" = 80 sts.
Am I wrong? I'm just really confused. I'm also not very good at math so I'm seriously second guessing myself over here. But no matter how much I try to figure out what I did wrong to gain those extra inches, I keep coming back to the same conclusion. But perhaps my row gauge being off a bit had something to do with it too?