I think you just need to practice more. I haven't been practicing lately, but it's good to practice so you will remember more fluently!

When i'm learning a new language every time I learn a new word I write it down and then study it until i'm confident that I know it

Watching films in the language (with subtitles or not), listening music, trying to translate something and check it, reading in the language like articles and books, finding a friend to talk with, writing short stories (somebody can check it).