Nobody on here knows your T like you do. If you feel what your T is doing is okay, then it can well be that you are right, we can just speak from our own experiences.

I can give you an example of something similar that I experience and how my T handles it: I have problems handling my emotions, especially with having too many emotions over nothing at all. We discussed my childhood a bit and we talked about how my parents didn't show much emotion ever. My T then said something like this: It could be that your parents caused your issues with emotions. We can't know for sure, but it sounds like a plausible theory. But we're here together now to learn how to solve these issues.

My T gave an opinion of why I have my issues. He can tell me that it might be that's what happened. And then we work on resolving the problems this created. But my T doesn't go and talk to my parents to see whether they actually don't show emotions or whether it's something in my head where I can't recognize their emotions or whatever. Working through my problems is done without ever needing to confirm this.

So if I translate that to your case, what I'd kind of expect a T to do would be for example say 'okay, you have lots of issues with certain topics regarding sex, how do we resolve your freak outs around these'. For that you don't need to know the correct root of the problem. Ideally of course you do. But if you can't remember, it doesn't matter. Your T isn't a detective, she shouldn't have to dig for reasons as to why you're the way you are. It's fine for her to suggest something as a theory. But it's just a theory. Psychotherapy does not usually rely on confirming these theories, since that is most of the time not even possible. It only matters what the truth is that you find within yourself. And in my opinion a T should help bring that truth out, not find support for their own belief from people outside of the therapeutic relationship.