I usually make lists for my students. These are lists of words they have difficulty pronouncing properly, words which they forget the definition for, and lists of expressions. I suggest you do the same. If you compile a list of words you find difficult and repeat them every night before bed, they will become words you use effortlessly. People seem to think they have a good or bad memory. The truth is humans are creatures of habit; if we do something repetitively, we become proficient at it. There is no way around it. Therefore, iff there is a problem or difficulty, work on it. Nothing is achieved without work. If you really want to improve your English, you have to start doing the work. Won’t you feel a lot better when you aren’t searching for your words?