I'm Not in MA Yet, But at Least There Are Cats

I start every scene with a plan in mind, and occasionally the characters behave, and the plan in mind becomes the scene on paper. But more often, I discover something I didn't realize about one of the characters, or an interaction doesn't play out with the particular type of feeling I thought it would, and the scene starts to go off course, and I have to chase after it, and pages get written and then crossed out, and I can't figure out what needs to happen, and I begin to get Extremely Grumpy an