A 7-year-old girl with a confirmed diagnosis of Autism Spectrum Disorder (moderate severity) is referred to you for management. She attends a mainstream school with a teaching aide. Her parents report significant anxiety during transitions, difficulty with peer interactions, and occasional aggressive outbursts when frustrated. She has no seizure history or intellectual disability (IQ 85). Her pediatrician has already ruled out thyroid dysfunction and lead exposure. What is the most appropriate next step in management?