Observe people with good social skills - you will discover that
they interact (no doubt), but they also display good listening
skills and their body language is positive. 
People like you are very self-perceived. You contribute reasons for
what's happening through personal deduction and reflection. But
generally, its very clouded, because your emotions comes into the
picture. (Dread, hate, etc).
Prefer working with older people? Have it ever occur to your that
these people would require the same form of social/interaction
skills you would empoly on others as well? (Irregardless of whether
same age or not).
So what's the real problem?
Its within your psyche which contributes to your subconscious
hidden behavior that you don't realise.
You feel that the
wavelength is different from your classmate as you feel that you
don't talk alot and probably different topic as well. In your mind,
when it comes to your group of friends, you automatically shut off,
which will in the end display, without you realising, body language
that signal 'l-am-a-loner.' vibes. Others will catch it
subconsciously and will not attempt a good chance to know the real
you because their subconscious mind reads the vibes and acknowledge
them.
Then you pick up their body language and feel that they are just
merely classmate and nothing else. You futher distance yourself.
And the whole damn cycle continues.
Its not the problem of being on the quiet side - I have friends who
are so damn quiet, yet they don't quite experience the same problem
as you.
Advice?
You can wall your mind with this preception and forever be stuck in
the cycle. The keyword is 'OPEN MIND.' Recongise and acknowledge
that everyone is different, therefore we learn, share and gain from
one another.
In a group when there is a conversation between people. Listen to
the speaker. Nod head/show body language that you agree/disagree.
(Raise eyebrow, etc). Here's a secret tip - if you can't be a
speaker, learn to be a good listener. It really helps alot to blend
in whatever place/society you are with. Gradually when people knows
that you are a good listener, they will talk to you. Then from
there, you return their conversation decently. Of course, you have
to show interest in what you say and listen, if not, people
wouldn't bother at all.
Cheers
