I'm also an Autistic adult and I have 3 boys. They're now 31, 29 and 27. Time really does fly! I can remember their little plays and basketball and baseball games like they were yesterday. It's hard to let go of those times, but one thing that really helps me when I miss those "little kid" days is seeing what wonderful adults they've become.
You have so many fun things to look forward to, graduations, college, more graduations, first homes, marriages, grandbabies....wheee!!