Toddler speech delay, brain damage?

[soworriedaboutspeech]

I am hoping for some help and advice as-well as getting some worry off of my chest I suppose.
My son is just 3 years old. He had a difficult start to life due to a rare birth-defect affecting his lungs and heart. After a lengthy stay in NICU and many surgeries later, this problem has been 'fixed' and after a rocky first 2 years in and out of hospital my son is now physically doing great!
His speech is very delayed and I've been told that he is closer to that of a 1 year old. He has been with speech & language therapy/portage since he was 2 years old and also attends mainstream preschool a couple of mornings a week.
My husband and I have always been of the opinion (and previously advised by specialists) that his speech delay was just that, a delay caused by his difficult start in life and that he would get there eventually.
Today I've been told that the new worry is that his speech problem may be caused by brain damage. My son had sepsis in NICU and difficulty in PICU with ventilation both of which could have affected his brain. In every other aspect my son is a clever, confident, mobile little boy and this has come to me as a big shock. My son has been given 6 months to see if his speech improves and if not we will go down the route of brain scans/MRIs to check for any damage. 6 months seems like such a long time to be worrying about this.
I was wondering if any other children that have had problems/delays with their speech have managed to pick it up quickly/surprise everyone and start talking? Or if any child has been delayed with their speech after the age of 3? Or if anyone has found themselves in the same position as myself with their child.
My sons paediatrician is fairly confident his speech delay isn't related to Autism as the speech delay is 'isolated' and his social behaviours are the opposite of what they would expect from a child on the spectrum. I only mention this as google (I know I shouldn't google) points me in this direction and it's so hard to find information surrounding my sons set of circumstances.
I would really appreciate any advice.
Thank you.

Bump

Hi OP, I'm sorry I don't have useful experience but my DD is 3 too and a little speech-delayed. She was born with the chord around her neck and needed assistance to get going. Docs did consider NICU - this fortunately wasn't required and she's developed fine (albeit on the later side of gross motor and now speech) but I've occasionally wondered if that slightly difficult start could have affected things. Hmm. Anyway sorry for the ramble! Hopefully my waffle will bump your post!

It always does annoy me when you Google sppech delay and it comes up with autism as autism is not a speech disorder. Children with autism might have delayed, poor, normal or excellent speech abilities just like children without autism, so a speech delay in isolation is a very poor indicator of autism.

My son spoke his first very unclear words around his 3rd birthday - he had s&l delay but no problems at birth/health wise - it took about two years of speech therapy and early intervention for him, I agree with AladdinMum Dr google always seems to suggest autism but there are many different speech disorders.

Thank you everyone for your helpful replies. I agree with delayed speech automatically being linked to Autism is very frustrating.
I think the shock of hearing the words 'brain damage' has worn off a bit now. My son is amazing regardless and even if this worst case scenario is correct I know he will be ok! However, I'm still hopeful he will wake up one morning and start talking away. It's all there in his head, he knows the words and understands what's asked of him he just doesn't verbally communicate.
Any advice on how I could help my son along? I have downloaded some phonic sound videos and using verbal prompts every time we play/do activities. Thank you x

I found the website teachmetotalk really helpful, there is a checklist on there somewhere of the pre-verbal stages they go through so you can see whereabouts your child is and do activities aimed at that area.

Otherwise seeing a speech therapist who works with pre-schoolers weekly really helped us, NHS provision isn't so great here for speech therapy so we went privately.

Thank you very much @Esse321 that's really helpful

Hi, my son is 2, had a tricky start, and was in NICU. Is there a chance your son could be deaf? Did he have an ABR hearing test upon leaving hospital? I don't want to worry you unnecessarily, but that is what happened to my son, and would explain the speech delay?

Maybe a bit mad, sometimes things like duolingo help.
The kids version, it says stuff asks you to repeat back