How do I get my hips more than 4" bigger than my waist?

something I really worry about. My Bust 43" My waist 35" but my hips are only 39". The ratio of waist to hip is bothering me as my Dad died young of massive heart attack. I am 11st 7lb and 5ft 5". Every time I weigh 9st 5lb which is listed as my ideal weight, my hips go down to 35" but my waist is still 29" bust is 37". I look terrible as my trousers hang at the back and everyone says I look too skinny.I feel this is better for my health though as my waist is smaller but I can't stand the comments re my hips and it gets me down. Is there any way I can even things up. BMI 27 at the moment.