Good luck op. You seem to academically understand what you're doing. "600 calories of chicken is a huge amount of food" is the greatest thing I have heard a fat person say.
From a mental perspective, relying on will power alone to cut out all the rubbish food is an immense task. I guess the only advice I would offer here is if you fall off the wagon and eat a donut, don't let it derail your entire plan and eat 10 donuts a day for a month. Everyone gets drunk and devours a pizza every now and then. Just don't do it regularly.