18 months stopped talking?!?

Elias

My son Elias use to say momma and dada at 7 months very clearly and he hasn’t said it in months and now he’s 18months. Does anyone know if this is regression autism or just late talker. I’m waiting list to book our first speech therapy appointment. If anyone can let me know what they did in this situation or have any insight. I’m loosing my mind waiting on our appointment.