My brain is Scattered

I'm on Italki because I want to improve my English skill. My friend ever even told me that I have to think in English, not in my native language. At that time, I don't understand how to think in English because I have no words. Even if I know some English words and know the grammar though, I have to use those words contextually. It's hard for me, because people around me is are (people is a plural noun)not speaking English. The only best way for me is watching the English movies or listening to the songs (since you're not being spefic you wouldn't need to use the article "the"). It might be not worked not work too if I got the wrong movie, I meant many movies or songs in English are using use the slang or their grammar is wrong.
I'm still trying to think in English daily in my daily days. But it's hard for my to concentrate because I'm confused which words I have to use. English is unlike 'bahasa', because English has lots of similar words. It's not rare I got my for my brain to be scattered when I was panic because I couldn't speak it out what I wanted to say and I don't want to make my partner waiting for me too long to finish my speaking (or you could say "for me too long to finish my thought").

I want to know from you those who have an advance English skill, is are my thoughts about learning-from-movie isue false? Thank you.