Dc2 (ds) is 21mo and I don't know whether his speech is behind.
He can only say maybe four or five words clearly. He says another four or five unlcearly (a bystander would have no idea).
He does a lot of "wah" "huh" "meh" type noises.
If we say a word and he repeats it he just makes the noise/intonation we make. So if I say "say well done!" He will do his wah noises but to the same rhythm.
His comprehension is good. I can give him instructions and he goes and does. He remembers stuff we do regularly. He knows a good selection of animal noises.
He just doesn't really say proper words!