I have had somewhat simular experience, however it hasn't just been limited to being unable to come out of my shell or whatever enough to join in or not being able to because of feeling so out of place....I actually have endured a lot of bullying and getting picked on over it as well, which has not helped my sense of self worth at all. I did not get diagnosed till a couple years ago and am now 25, so now I kind of have more understanding of what was different and why I found interaction in general difficult let alone actually interacting smoothly. Even so looking back at my childhood just makes me sad...doesn't matter if I understand now I still missed out, on really actually living my adolescent/teen years I more just trudged through it.
Also though while I did wish I was better at interacting and such as a kid, I didn't necessarily want to fit in with the popular crowd....but then part of why I had resentment was because they where jerks to me.
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We won't go back.