Remember what John said in a previous post:
"Suppressed feelings influence thoughts of the conscious mind more than the conscious mind can influence the suppressed feelings. If nagging thoughts of painful events keep coming up, it's just a sign that the suppressed feelings associated with the events have not yet been substantially released through processing."
When I have been faced with that issue, what I have done is to focus on the feeling regarding the mental movies that play themselves. I find myself going into the stories and then going back to the feeling. When I am consistent in going back to feeling in the body, the mental stories drop until no stories are played back or if they are played back it doesn't matter anyway.
Sometimes I find that when I am working on a feeling some images appear when I am releasing, they are just memories coming up, I just allow the images to arise naturally and dissapear organically with the process.
I guess that maybe you are approaching the work with the intention of solving or getting rid of some "problem or issue", from that perspective one tends to fight or control what happens, hence, the thoughts of "doing it wrong". When you feel the feelings just because they are here and not because you want to attain some preferred state, then the questions and doubts dissolve and you trust the process and the very process guides you. That is what I have experienced.