I just crossed the over-30 threshold today. I've known about my autism since I was little and have somehow always been conscious of how it's affected me, although the spectrum has expanded so much since the late '70s, so I think a fresh diagnosis could be in order.
Have I missed out on a lot? Well, some, I guess. No dates or girlfriends, very few real-life friends until recently, and not a whole lot of self-esteem. OTOH, I've progressed much more than any doctors would have thought - I'm living independently, holding down a job and acting pretty much 100% normal.