I don't know about missed out, exactly, but it is different. My eldest daughter is classed as disabled, but in the scheme of things, although she gets High Rate Care for DLA, she isn't severely disabled in that she can walk, can talk, can eat and is toilet trained.
But having DD2 20 months later (and, now, DD3 also) I can see how different things are for her/them.
DD2 just intuitively picks up behaviours, actions, words etc., despite only being 22 months old. In some ways she is more advanced than DD1 (3.6) already. I am having to prepare myself that DD2 is going to outstrip DD1 very soon. DD1 has 1:1 at preschool, and learns everything in quite a rigid way.
However, when I see DD2 wiggling to music in a way that DD1 can not, or seeing DD2 effortlessly walking on tiptoe, when DD1 can fall over her own feet walking across the lounge, it actually strengthens my love for DD1.
DD1 is just starting to name squiggles on paper. Nothing is recognisable, but it was so funny when she said she would draw an 'elephant', and after 1 long squiggle, said "Uhoh, oh dear, bit like dog..."
I don't know if this is at all helpful. I suppose what I am saying is that you might find that if you have another, in a strange way you will not only experience all the 'NT' things of an NT child, which people might say you are missing out on, but you might find that you experience a whole new side of the love you have for your current DS.