I don't really have any answers to your second question, but I can relate to the first part of your post. I got burned out about five years ago. I had been assiduous about my diet for 2 years!! Then, I got a new job and my father died, and I just couldn't seem to keep my diet up because I had devoted too much energy to it prior to those events. Lesson learned: My diet (as in, "way of eating") must become just part of my daily routine, like brushing m teeth, walking my dogs, etc. Long story short, I regained ALL the weight I lost. It's just the been last month or so that I've had the heart to really get restarted.
This time, though, I am following the KISS method. You know "Keep it simple, stupid." I have a tendancy to become overzealous about most things in the beginning, and then I think about them so much that I eventually burn out from them. So, I'm not going to worry about anything other than calories and generally making good choices.
Also, I just read this article . . .
. . . and it sort of confirms for me that micro-managing weight loss by tracking all the nutritional factors isn't really necessary.