How to lose lower abs? ?

I am a 15 year old girl with a lower ab problem that runs in the family. I constantly do crunches at different inclinations but get no results. I have a 4-pack but once to the lower abs, I get flabby. I have about a quarter to half an inch of fat in my lower abs. How can I lose it? It really bothers me because I cant lose it and because of it I appear fat and it doesnt help that I have a short torso, am 5' 2", have wide hips and small boobs. (makes stomach more noticable)