I aced all my courses during my undergrad years and published a paper with the help of others, but my writing and vocabulary still suck. I was born and raised in the US, but my writing has gone downhill after taking a break from school after I graduated. Now I am looking at grad school. I may actually get accepted, but I am terrified that I regressed into a poor writer. I love reading peer-reviewed articles, but they intimidate me whenever I see many words I do not know.

Admittedly, I still have no clue when it is appropriate to use "a priori," "de facto," and "a posteriori" in a paper or a sentence. Even after having read the definitions.

Is there something wrong with me?