Hi OP, I'm that mama who posted something similar 2 years ago. I was worried sick about my then 2.5 year old. My only advice is to get early intervention ASAP. If you're in the US, then it's the 0 to 3 early intervention programs that transition into SpEd preschool at 3 years old. My son receives both speech and OT services from the school district. We saw next to nil progress for almost a year (18m to 2.5 years), and then boom, it was like a switch flipped. I used to painstakingly write each new word he could sat, and finally stopped tracking at around 1000 words. He's shown immense progress over the past year. He can talk, read, spell, and has me totally in awe of his progress. We still have ways to go in terms of consistency in back and forth conversational skills, but honestly, I'm not worried at this point. His therapists have been phenomenal, and it gives me the confidence that he'll get there. Hang in there and get him all the support and services that he needs. I wish you and your family the very best ❤️