What can I do to become a fluent English speaker?

Dear sir,
I have difficulty constructing sentences in my head and have problem expressing myself during a conversation even though I know a lot of vocab words? I've tried to immerse myself in English and also listen to vocab builder cds regularly. It's frustrating because the progress is so slow that I can only say a few simple sentences in English during conversation and can't seem to remember what I've learned and put it to use.
I watch movies of all genres nearly everyday to widen my vocabulary and have made the effort to learn popular slangs or specialized terms to understand the movies. I always watch a flick in English but with English subtitles on because the actors either speak too fast or their accents are too difficult to understand. Will that decrease my listening ability?
Even though I've been watching American films for more than 15 years now, I speak poor english. Is it because I have very little chance to speak English with anyone in 10 years? I thought what you learn through reading, listening and writing will also help you in speaking good English? Perhaps I have a bad memory or a learning disability. Please help.

[curmudgeon]

Well, you certainly don't have a learning disability. It is sometimes very difficult to overcome the 'plateau' in learning another language. All you can do is persevere. Your content is good.

[RobbieCook]

Your English seems excellent in written form. If it's only in conversation that you're running in to problems, I think practising speaking English will help, rather than simply listening to it being spoken.

[bigapplejin]

Hello,

Your written English appears to be proficient. but I believe that writing is one thing and speaking is the other even though they are related.

If you want to imporve your spoken English, you have to practice it.
The best ways is to make American friends and practice with them.