SO-OCD runs in every direction, and that is the tell
Straight people get it about being gay. Gay and bisexual people get it about being straight, or not gay enough. If this were about orientation it would not be so indifferent to the answer.
A thought turns up, what if I am not what I thought I was, and instead of passing, it asks to be settled. Since then you have been running tests. You look at someone and watch for a reaction. You watch for the absence of a reaction. You scan your body for any flicker and take whatever you find, or do not find, as a verdict. You replay your entire history for the moment that proves it: a crush at fourteen, a dream, something you once found funny.
It runs in every direction
Straight people get this about being gay. Gay people get it about being straight. Bisexual people get it about being one or the other, or about having got their own life wrong. People who are entirely settled in their orientation get it about being secretly not, and people who are still working it out get it too, as a layer of dread on top of the ordinary question.
That symmetry is the tell. If this were really a question about orientation, it would not arrive with such perfect indifference to what the answer is. A person genuinely working out their sexuality is usually drawn towards an answer, even a frightening one. This theme is characterised by wanting the question closed and not caring which way, as long as the uncertainty stops.
It is not about the answer
There is nothing wrong with any of the answers here, which is why the treatment is not aimed at finding one. SO-OCD is the inability to close a question, which is what OCD does to whatever you would find most disorienting to be uncertain about. For some people that is whether they locked the door. For some it is whether they might harm someone. For you it is this. The mechanism is identical, and so is the treatment.
The tests and why they fail
Every test you have run has produced an ambiguous result. Attention aimed at your own body reliably produces sensation there, in anybody, about anything. So the groin check finds something, and the something gets read as a verdict. Attention aimed at your own desire reliably makes it hard to find, because desire does not survive being monitored. So the test of whether your partner still does anything for you produces nothing, and the nothing gets read as a verdict too. Every direction is incriminating, and none of it is evidence. It is the checking producing what the checking looks for.
That is worth an early session on its own, because a great many people conclude the worst on the strength of a physical response that the checking itself created.
The avoidance
Around the testing, the avoidance builds. Changing rooms. Certain friendships. Particular films or actors. Conversations that might turn to the subject. Each avoided thing brings relief and teaches the brain the subject was dangerous, and the list grows.
What treatment does not do
First, plainly, because people arrive braced for it: this treatment has no view about what your orientation should turn out to be, and it will never try to steer it. Conversion practices are unethical, ineffective and harmful, rejected by every UK professional body including mine, and they are the opposite of what happens here. If it emerged in the course of therapy that you were gay, straight or bisexual, my response would be the same in every case: fine, and how do we get the checking to stop. I will not be running my own quiet assessment of what you really are while you talk.
What treatment does
The treatment is CBT with exposure and response prevention. Our target is the testing, not the question. We map the cycle: the trigger, the thought, what you take it to mean, and everything you do afterwards. Then we withdraw the compulsions by agreement, and let the question sit unanswered until it stops behaving like an emergency. Inference-based CBT fits this theme well too, because the doubt is built almost entirely out of reasoning about what a fleeting reaction might have meant.
Some people finish therapy certain of their orientation, some finish comfortably unbothered by the question, and both are fine, because the goal is the compulsions stopping rather than a conclusion. If you have been running tests for months, there is more on how I treat sexual orientation OCD.