In my opinion he is still a little too young to get a dx, but that doesn't mean you should stop the therapy. My 5 year old DD has verbal apraxia. Children with autism can have it, but it can come separately too. Verbal apraxia effects the motor movement of the mouth. The child knows what is being said to them and knows what they want to say, thus the jargoning. Your son can do a lot of things my DD still has trouble with, like waving goodbye. Perhaps you should talk to your SLP about this as a possibility. What have you done with him therapy? Has he started learning the PECs picture cards?
I asked his therapist about apraxia and she said absolutely not. I have flash cards that I use with him at home that is from your baby can read and he knows every action or animal... Like it shows his nose an he points to his nose or arms up and he will hold his arms up. He does not basic signing for more, open, all done, up. His therapist told me at our last visit that she had talked to his OT therapist an they are both now just thinking it's speech delay bc of everything else he does so well. I just need to be patient I guess... It's so confusing at what to think about it. She tells me that if we were to get an eval done at this time she believes his dx would e PDD-NOS.
Is he doing any better now?
My daughter also has speech apraxia, and your son sounds a lot like her. She would only babble until she was a little over 2. She has been in speech therapy (early intervention then therapy preschool) since she was 18 months old.
Just keep working with him. Try teaching him some sign language, that helped us tremendously.