Is this sweater knit in the round or in pieces? Does it have a ribbed bottom? Check your library for Big Girl Knits, it has a lot of info on knitting to accomodate various body shapes. It has helped me figure out some shaping details to work with my body shape.
knittingdaily.com has some great articles on how to determine fit (but also might entail doing some pattern alterations) and has super galleries to show how actual patterns fit on average ppl with various body configs.
Measure the high hip area then and see how much difference between that and the bust. What you could do is leave the side seam open for 2-3" on the lower edge and knit for the bust measurement.