When women get pregnant a hormone claled relaxin is released. Basically it loosens all your joints and is what makes us waddle and be so clumbsy. Part of the reason for it is your hip bones seperate and become wider to accomidate birth. That is why some women can diet all they want after kids, they never get back into old jeans. It's a matter of bones, not fat.

I have the same problem with wide shoulders you do. Any outfit with shoulder pads, those are the first to go. Even without them I resemble a line backer. Now if I could just get the huge chest to balance it........