Good luck, there is a smart quote from a song that says "The race is long, and in the end it's only with yourself". If you care about making this happen, learn to forgive yourself and keep striving.
I will say I've been on a very strict pre-op diet (my surgeon does a full 2 weeks of clear liquids) for 11 days and I'm down 24 pounds. But I am starving all the time. I have been as irritable and unpleasant as I can ever remember myself being. I really do hope it gets easier after surgery.