Quest, first of all, I admire your dedication
and tenacity. It is good that you are aware of
your strengths and weaknesses. It seems that
you need lots and lots of practice. All
the people who responded above have
very valid and useful points. Have you
observed if you have dry lips and rapid
heartbeat even while speaking in English
with your friends? Or only when speaking
with strangers and superiors - that is,
someone you think will judge you?
If you are able to practice one-on-one
as tdol suggested, that would be very good.
So, language exchange is a very good way.
Next, I agree with Ouisch about speaking without
trying to form sentences (thinking). This will
come if you expose yourself to the language a lot
by listening to the news and watching movies.
I am not a linguist, but somehow there is some
relation between listening and speaking. That is
what we do when we learn our mother tongue
as a child, right? We don't learn grammar rules
and correct accent, but we can still learn to
speak. That is NATURAL language to me.
Finally, try to find a Toastmasters Club in
your area if you can. You can find a club
from their website -
http://www.toastmasters.org/
The advantage of going there is that it helps
to improve your communication. It is NOT
a language school, and it seems you don't need
one. You just need a supportive environment.
At the Toastmasters, you can learn public speaking
and giving short extempore speaches. Since
everyone is there to improve, and they have
specific ways to help by way of suggestions
(about language, body language, if you exceed
your alloted time, etc), and since there are
senior members to help, you can learn a lot. Once
you can speak to a group, speaking to
individuals won't be a problem. :)
Good luck to you.