The long lasting secret

Lydia Lenard, a girl whose family is threatened by an unknown person, keeps everything within her and is at the verge of bursting but is helped severally by her best friends, Dylan and Tia. Whilst facing personal problems that made her body change, and none of these were due to puberty.
What do the signs lead to?
What do they mean?
And why the hell is she inlove with two boys at the same time,