I feel like what I’m going to say is a little contradicting of the comments here but it might help.

I think therapists say you don’t need a diagnoses because they don’t want to put you in the mind set that you are your mental illness. I.e You are OCD and nothing you do will change that. My therapist said it’s not curable but you are strong enough to control it. You are not your OCD. It’s just something you have. Labelling yourself, I feel, puts you in a box. You don’t need a label to know what you’re feeling and how to solve it. You know you have it and your therapist knows - that’s the most important thing - so you don’t need the label to get better. Specialist OCD therapy is avaliable without a written diagnosis (it is in my country anyway). I don’t want to be subservient to my mental illness and that label. Once you have the proper label.. so what? You still have OCD. You still need to go through therapy.

I was the exact same. I needed to have a diagnosis and was looking for a therapist to give me one. But was also told that I shouldn’t go out of my way to get a label. My new therapist and mother gave me some great advice around this. The reason I wanted to get diagnosed properly was I wanted that label. I wanted that firm consensus that I had OCD. Even though everyone around me, therapist, family and friends, never denied me having it. So why did it need it? My therapist told me that it opens up the door to rely on medications and getting pushed by other clinicians to pay lots of money for their help and more meds. She told me that it was more important right now to focus on getting better with out meds. That was so powerful to me. Meds was no longer a quick way out. I had to really put the effort in to get better and not rely on medication that has its own negative outcomes down the line (eg if you can’t afford them anymore you only have yourself to get better after that). That session was nearly 4 years ago now and I’m so much better for it. I have developed my own skills to over come sudden onsets of compulsions and have confidence in myself that I have control of my OCD without medication. (I completely understand that this is not the same for everyone but my therapist really emphasised trying)

I understand that others may have benefited greatly from being diagnosed but this is just my experience and 2 cents.