The first year is always harder I think. My dd is now 5 and I can't believe the little person that she has become.
She "failed" her 9 month development check up, couldn't sit, crawl, pick up small things, etc.
She was diagnosed with global developmental delay (both fine and gross motor skills) and it wasn't until she was nearly 3 that we found out that she has Sotos syndrome which causes overgrowth in the early years and developmental delay.
She is now 5, goes to mainstream school (with a statement and one-to-one help) but, if you had told me how far she would have come by the age of 5, when she was only 1 or 2 I would not have been able to see it.
We all want our children to be the best they can but Sasha has taught me to love and admire each child for who and what she is. She is my youngest of 3 (others are now 14 and 10) and she may not grow up to be a rocket scientist but if she grows up to lead a happy, independent (maybe) life then I will be so proud of her.
She may not be the child that I thought she would be but as long as she can be the best she can (whatever that might be) then I will be proud.
I know it is very hard not to worry about the future and what you say about children the same age, our next door neighbour has a little boy who was born on exactly the same day as Sasha and seeing, even now, what he can do and what Sasha cannot do (ride a bike without stabilisers is one thing that comes to mind) I feel sad that Sasha cannot do that but I take pride in the fact that she is a lovely, sociable, outgoing child who will do anything for anyone.
Don't focus too much on what Seb cannot do, try and focus on what he can and how far he has come. For other children what is a mild developmental stage, for Sasha it was a monumental leap (crawling at 15 months, walking at 18 months) but she did get there in the end.
Take care and don't worry too much about the future (easy to say, I know) but 5 years on I wish someone had said those words to me.
One way I think of Sasha and explain her to other people is that I think of her as "being on a bus". We all know that some buses run late and Sasha's is running a little bit later than "normal". Her bus is a little behind (the bus being her development). I like to think that as long as her bus arrives (whether that bus - development - be sitting, walking, talking, I will be happy). I know that her bus (development) might not actually get to the end destination and it might break down a bit before the end, but as long as she makes it nearly there and makes it there in most circumstances, I will be happy.
Hope that makes sense and I haven't waffled too much.