You've been writing a novel without any plot? I don't know if I should be impressed.

Even if the story is about the growth of a character (as pretty much all stories are about), you still need some kind of plot as a reason to propel their growth. For instance, looking at a very flimsy plot: The Last Song by Nicholas Sparks. The plot is basically girl moves to new place, meets boy; boy is responsible for burning down his father's whatever. It's a romance novel, mostly about the romance between two characters. But a simple plot was still needed to move things along.

Reading other books will help, but look at your own story. See where a plot makes sense.