Do you find you just can't give yourself a break from thinking about what you're doing wrong when you're trying to lose the weight?
Why is it that you remember the bad and not the good?
It most likely has to do with the fact that you're no longer sailing along (the good). You've run into a snag and this puts the possibility of failure too squarely in the picture. It's this "too squarely in the picture" experience that is causing you to be plagued by these disquieting thoughts.
But everything, especially when trying to lose the weight, isn't smooth sailing. You should know this.
You'll have to live with some persistent, unwanted thoughts--seeing more of the bad--when you set heartfelt, clear and specific goals that you are finding hard to meet.