What am i doing wrong =(?

i have had a miscarige befor it hurt me very bad,i look at this day from now on and wonder to my self i would have a baby with me now it hurts to think that me and my boyfriend have our own house and are financialy settled we are trying for a baby now i lie in bed at nite and cry to my self thinking what am i doing wrong.is it i carnt conceive i dont no please some 1 help me jess xx