I am happy to impart my two cents, but I am not an established writer myself. I am just another passionate writer just like yourself.
I started writing in my teens, too. So considering my age today, my only advantage is the many years of practice I had, - although as of late, finding time to write is a luxury I cannot afford often.
If you have a clear visual of the plot in your head, the right words will come naturally to you.
As for finding the right words, other than reading more, the dictionary and thesaurus are a writer’s bosom buddy. I have lost count of the times I stopped writing a fic halfway just to flip through them. As a bonus, you pick up a few new words along the way. ☺️