Like the heart and mind of many a 15-year-old girl, “I Am Not Your Perfect Mexican Daughter” — now showing at Denver’s Kilstrom Theatre — brims with feelings and thoughts, fears and dreams. Unlike most teenagers, though, Júlia Reyes (Rosa Isabella Salvatierria), the play’s lead character and our guide into her roiling and prickly world, has recently lost her sibling. The resounding blare of a semi signals how 22-year-old Olga (Heather Lee Echeverria) — the perfect one — met her death. Júlia Reyes (Rosa Isabella Salvaterria, left) and the spirit of her sister, Olga (Heather Lee Echeverria).