Are You There God? It's Me, Margaret.

Margaret (Abby Ryder Fortson) moves with her family to a new city and a new school, where she meets Nancy (Elle Graham). Nancy invites her to join her secret club, but she tells Margaret that if she wants to be a member, she has to wear a bra. In health class at school, the girls are horrified when they learn about menstruation and when Margaret has to buy her first sanitary napkins, she prays that the cashier will be female. Instead, it turns out to be a teenage boy. It's tough being a preteen girl.