You can speak English fast and fluently even as the native ones.When speaking,you needn't care much about word-choice.You should try to use all words you know.You also should practice everyday.Speaking a foreign language well takes much time.
Choosing topics to discuss is important too. Try to renew topics to avoid boring feelings. Variant topics will help you know more words.If you don't know words what you mean to say, ask your friends or look them up in a dictionary.Don't be ashamed if you don't know some new words !
That is my experience in learning English-speaking and I hope it can help you.
Best wishes !