Once upon a time, well two years ago during my first NaNoWriMo attempt, I’ve finished 50k in 12 days. It means I was writing 4–6k per day every day and afterwords my brain needed serious break for a week or two but if you ask about a story it was OK. Not garbage that some people would expect. So 10k behind is like three days of intense writing, not perfect one but good enough to be corrected later. So I support you in not giving up and I think that 50k for you is more probable than you think. Good luck!