Oh, girl, I feel your love of the Thin Mints!
We recently had a Girl Scout knock on the door to take our order. My husband asked if I wanted the usual Thin Mints, and I looked at him like he was nuts; it was one of the toughest things I've yet had to say no to, because I freakin' LOVE those little discs of crisp chocolate minty goodness.
You did well to eat only some of the sleeve and consciously decide you'd had enough. That's a win, not a fail! That's the kind of behavior that "naturally thin" people often exhibit, so it's a great sign that your new eating habits are so ingrained now.
Never
ever feel guilty about not feeling guiltier.