27 month old still not talking (long post)

So my son is 27 months and is still not talking. He has been a late bloomer on EVERYTHING and is an only child. We’re not big on having him watch tv, but I am guilty of downloading “learning” apps on my phone and having him play them. My nephew is about the same age and that boy talks all the time 24/7 and is just go go go all the time. His parents sit him in front of the tv a lot but I think it’s helped him. He knows all the songs from little baby bum and can count and knows his abc’s.

Anyway my son understands me, if I tell him to bring me something or throw something away, or if I say let’s go outside he understands me just fine. He’s a chatterbox and babbles a lot, but the only real words he says (more like mumbling really) are thank you, ball, and bye. i think in his mind he thinks WE’RE the problem because we can’t understand his little language lol. His pediatrician referred us to a speech therapist and my husband wanted to wait a few months to see if he starts talking out of the blue 🙄 I wanted to enroll him ASAP because what harm could it do PLUS it’s free. It’s like he doesn’t want to admit that he’s taking a while to talk. He’s finally enrolled now, and after all the tests and evaluations he FINALLY starts his first session this week! Is there anything I need to be doing to help him even more? We read to him, talk to him, sing songs, play... I just don’t know what else we can do with him.

I remember my little sister was around 3 when she first started talking, but she had me to translate everything for her so she never felt the need to talk. But my son is an only child.

And for Christmas my SIL got him a “girls autistic robot toy” and her husband was explaining how it’s supposed to teach kids to talk. I just thought that was kind of rude, (nothing against anyone with autism) but maybe they were just trying to be nice/ helpful and im justsensitive lol. I’ve brought up the topic of him having autism to his pediatrician and although they can’t really tell from him only being 2 she said he doesn’t show early signs of it.

How long did it take your kids to start talking? And how long did it take til you noticed progress from speech therapy