Though I've not used the AFL system that this forum is for - I think I can at least relate to what you are going through.
In order to build up momentum toward a feeling of unworthiness, you would have to accept your unworthiness as truth right? So having built that kind of momentum simply means that you have a habit of accepting unworthiness as truth. Therefore, to say to yourself "I'm worthy" would seem to you to be a lie for you have grown so accustomed to accepting unworthiness as truth.
If you persist in believing in your worthiness despite the fact that it feels like doing so is "lying to yourself" you will eventually come to the point that you are at now. Each part seems to be of equal truth. The very fact that you are experiencing this kind of "teeter totter" seems to indicate a good degree of success in breaking your old habit, yes?
So where to from here? Have you heard the story about the indian brave and the two dogs at war within him?
There was once a young brave who was not growing up. He could not do anything that the other braves could do and seemed to be too afraid to stand up for himself. A wise elder decided to send the brave out into the forest to fend for himself, forbidding the brave to return unless he had learned what he needed to learn. After three months in the wilderness, the young brave returned and approached the elder. To be sure that the brave had indeed learned what he needed to learn, the elder questioned the brave.
"What have you learned?"
"There are two dogs within me. One is all that is good in me, the other is all that is evil in me. I am capable of each of them, but they are constantly fighting within me. I have not been able to achieve what I know I am capable of because the good dog can never surface because the evil dog is always fighting with it."
The elder nodded, clearly the brave had learned something - but was it enough?
"Which dog wins?" He asked the brave.
The brave paused. He was stumped. Had he not learned enough? But then the answer came to him as sure as dawn comes to the night sky.
"The dog that I feed the most, wins."
I know, I know. It's a lot of words to just say "keep focusing on the good." But that's the gist of it...