Thanks so much for coming here to PC to share your concern.
The first thing I guess I'd like to tell you is that I'm a 70 year old man who has had a life-long struggle with my gender identity. Plus, in conjunction with that, I've also struggled with a number of different things that might be described as fetishes. (It's a long story & I'll spare you the details.)
But I mention that simply to let you know that I'm not unfamiliar with your struggle.
You mentioned fearing opening up to your therapist with regard to this issue out of concern there could be an over-reaction that could make matters worse. However I guess my first thought is that talking through what you are dealing with is exactly what you need to do. Of course I obviously don't know your therapist nor do I have any inkling as to your relationship with her / him. So perhaps what this is coming down to is that the person you're seeing is not the right therapist to be helping you with this concern? And, if not, perhaps the answer here is to either find a different therapist altogether or consider seeing a second therapist specifically to deal with this concern.
I am sympathetic to your concern with regard to talking this over with your therapist. I've had some less than stellar experiences with therapists myself over the years. But at least from my perspective it is the guilt, & perhaps shame (?), over the thoughts you're having that is really the problem here. You haven't actually
done anything. And you're not a pedophile. Thoughts are just thoughts. And we all have them. You know... it wasn't so many years ago that looking at young ladies in skimpy bikinis was considered entirely normal & natural for heterosexual men to the point where it was sometimes celebrated in song! It's only been the last few years that it's become something to feel guilty about.
You asked if there was a way to change your thinking & have some control over your urges. I have to say that, at least based on my own experiences, there is no way to prevent thoughts from occurring, to stop them or "stuff them back down", so to speak. The answer, to my mind, lies in learning to accept them & simply allow them to arise-&-fade at their own pace without becoming ensnared by them. There is a practice I use toward this end that is referred to as "compassionate abiding". Here's a link to a description of the practice:
Relieve Distress By Allowing It: Compassionate Abiding 101 | Mindset: Perspective Is Everything
And then here are links to 7 articles, from PsychCentral's archives, that (hopefully) may also be of some help:
How to Sit with Painful Emotions
8 Tips For Dealing With Painful Emotions | Cultivating Contentment & Happiness
Several Ways to Sit with Your Feelings
A Technique for Feeling Painful Feelings
https://psychcentral.com/blog/when-y...dium=popular17
https://psychcentral.com/lib/shame-t...emotion/?all=1
https://psychcentral.com/lib/how-to-cope-with-shame/
My best wishes to you...
P.S. Here are links to 2 additional articles that discuss how to let go of obsessive thoughts & change toxic thinking patterns:
https://blogs.psychcentral.com/relat...dium=popular17
https://blogs.psychcentral.com/relat...memory-2-of-2/