No worries Toffee. Having lived in a world of SEN for a long time, I meet all kinds of parental reactions from denial to falling apart and everything in between, it is such an emotive experience.
My eldest is in his early 20's now, then I had a very big gap and have 2 younger ones 13 and 10. My experience has been different with all of them.
My eldest was about a year old, when I noticed he didn't really engage socially with everyone at a small birthday party. I had a feeling before this that something just wasn't right. The year that followed, I felt like he was withdrawing and becoming more distant from me. He had no speech, didn't follow my point or gaze, no social referencing, couldn't follow any instructions. He liked to be held and be close to me (we co slept for a long time) and did engage with physical play like rough and tumble and tickling with those very close to him. Others started to notice he was different, he didn't call us mum or dad, he didn't really play alongside or engage with other children. I spent all my time speaking to him, pointing out, naming things, taking him to places. It felt like I was hanging on to him for dear life, to stop him drifting further away. The Health Visitors were not listening to me and to cut a long story short I went to the GP armed with pages of notes of concerns. This was just as the internet was emerging so I didn't have access to any online material. He was referred to the local hospital paediatrician and monitored, this led him into the speech and language nursery, but I was very shocked to find out he didn't have a diagnosis of asd, just global developmental delay (ridiculous bloody label) until he moved to another borough and into a special school and they told me. We swiftly got a formal diagnosis (much longer for CAHMS now).
To cut a very long story short, I use him as my example when speaking with parents who like you are wondering what on earth the future now means. He went to a selection of different school environments, from speech and language nursery, to mainstream with ASD units then onto a specialist school and time at a post 16 Section 41 (indepedant) school. So we really did experience every setting! He continued slowly to make progress, speech came and he was taught appropriate social behaviours and life skills. He has now developed as fully as he is going to be and whilst he does have a severe receptive speech and language disorder, he can speak with you and make himself understood and join in a conversation. His understanding is poor, he does have a very low IQ, but he has a well paid part time job (through a charity) helping out looking after sports grounds! He is now talking about wanting to live in supported living.
If I was to tell you when he was 3 years old, I was in such a dark place that I had thoughts that if both our lives were taken together, we would be in a better place together. But, it got better and I can honestly tell you that if only I had known how things were going to be. I won't lie, it has been hard, but everyone who knows him and his journey has said how well he has done and how lovely he is.
My 2nd son, I knew at 8 months something socially was not right. Totally different , he spoke well, understood instructions, had fab vocab, none of the stimming or odd behaviours. With him though, it was kind of the reverse, as he got older more started to become obvious. So fast forward to now, he has ADHD as well as asd which really is a bugger as it often causes more issues that the asd! He is at a mainstream with specialist asd unit, and is on course to do exams. His primary school were rubbish and I applied for his diagnosis and EHCP which he got in Year 5, after a very long wait with CAHMS and on my part a huge amount of pestering and chasing.
I would say it is never to early to speak to someone, or be assessed, to be given suggestions and strategies to help him with his development is always going to be valuable. Yes too to reading material, if he is on the spectrum, understanding that his brain is wired differently so he thinks differently, will help you understand how to help him make sense of his world.
I hope everything goes well on Wednesday, do let us know how you get on. Sorry this has been such a long post, I guess I just wanted you to know that as emotional as I know you are feeling now, it does get better. I have been doing this a long time and am about to have my 3rd assessed, they are all different and you do have to battle, but it wont all be bad days. 