Exact rules do not exist, since one definition of femininity is a matter of historical periods, personal taste, and of what is attractive compared to what is considered beautiful.
Are the girls we see in fashion shows (or in women's magazines) anorexic or are they a symbol of femininity?
Setting apart the values and the ideals that everyone has, it's important to know how to love our bodies and to rediscover the beauty of those body curves that we've learned to hate. Your body does not exist in order to be hated and modified but is there to be loved and respected.
You should try to find a better inner balance, because otherwise, you'll never be satisfied with yourself. The bad feelings that you often have, sometimes in imperceptible ways, are reflected in your body, which is the mirror of any suffering.