Focus Features announced it will develop “When I Was You” with Will Packer Productions. The project is based on the upcoming book from suspense novelist Amber Garza, described as a female-driven thriller.  Garza’s past works include “The Girl Frozen in Time,” “The Last Time I Saw Her,” and the “Prowl” trilogy.  Will Packer and James Lopez will produce under the Will Packer Productions banner.   The obsession starts on an ordinary fall morning when Kelly Medina gets a call from her son’s pediatrician. It’s a cruel mistake; her son left for college a year ago. The receptionist quickly apologizes: another Kelly Medina, who’s half her age, is a new patient.  For…