All of us possess a reading vocabulary as big as a lake but draw from a writing vocabulary as small as a pond. The good news is that the acts of searching and gathering always expand the number of usable words.
One of the really bad things you can do to your writing is to dress up the vocabulary, working for long words because you're maybe a little bit ashamed of your short ones. This is like dressing up a household pet in evening clothes. The pet is embarrassed, and the person who committed this act of premeditated cuteness should be even more embarrassed.