***Not a teacher***
(Please check your sentences and see if you can spot the few mistakes you've made.)
There are many experts here in this site who'll give you priceless advice. But, let me start with a few hints.
1. If you ever attend any classes or any gathering in which you discuss a topic in English, DO YOUR BEST not to think about the form of your speech in advance. A lot of learners, and the introvert ones in special, tend to make sure what they're going to say is perfect enough to sound great to the peers around, which will unfortunately decrease their fluency. So, even if the sentences are appearing in your mind try to deliberately distract yourself by paying attention to the speaker and focus on THE MEANING rather than the grammar. This may decrease your level of accuracy, but you need to do extra work at home to create a balance between the two.
2. Though this may be criticised as a mechanical outdated practice, you can also go for memorising 'short fixed expressions' and using them in your speech. This can gradually build up your confidence too. Uttering such ready-to-use expressions will make your jaws and tongue move faster, and naturally the rest of your speech will be, partially, adapted in terms of flow and speed.
3. One good practice, I think, is to improvise new sentences on the THINGS and stuff you see around the place you're in, and either describe them or (even force yourself to) say why you like them or hate them! This may sound a bit stupid, but the good point is talking about objects or people doesn't need reasoning or too much background information so your mind isn't under pressure while speaking. This way you'll gradually find it easier to 'utter' a stream of words, with less pauses. An example could be, you look at a piece of furniture and immediately try to say why you feel you love that piece! (Here, its colour, size, position, and the way it's used and even some more aspects can help you have ideas to talk about. Occasionally you may do it with a friend and check who's better at improvising such short speeches.)
You can, definitely, see some inaccuracy in my sentences, but I'm said by a few friends to have a good fluency in English. Many might not find these helpful at all, but what's the harm in giving it a try?! :)
Yet, please let's wait and see some sophisticated posts.