Do you just find yourself sometimes obsessed, thinking about the same thing and can’t stop? There was an interesting article in the (UK) Times on 2 September 2020 about George Ezra’s struggle with his “pure obsessional” thought disorder. The article then covered the debate about whether it is a distinct category of mental illness from OCD. As you might know, my view is that diagnostic criteria for mental illness are pretty messed up, and we don’t have much idea about what is going on in terms of brain dysfunction, genetics, and the effects of experience, and one of the best things about psychiatrists is that they can prescribe drugs (although even then some claim some drugs may do more harm than good). I think it’s very hard to disentangle different types of mental illness, and depression and anxiety disorders are one big blob of unwellness that manifests itself in different ways in different people at different times.
I am definitely inclined to “Pure O”, but I still have some compulsions, albeit currently weak ones that are not too dysfunctional (such as checking the door is locked in multiples of three). The key thing is that the compulsions don’t trouble me, but the obsessive thinking is horrible. When I was younger though my compulsions were much worse – going downstairs in the middle of the night when I was 12 or so checking that the front door was locked maybe a hundred times (although it would have been 99, a multiple of 3, or 81, a nice power of 3, and once or twice 243 times). I was also obsessed with the idea that other people could read my thoughts, even though I knew they couldn’t. I sat in the back of my uncles’ cars and worried that a passing driver would misinterpret my hand posture as a V-sign, and would then track me down, so I would mentally say “sorry sorry sorry” (again some power of 3 times). It was the different world then. I’d never heard of mental illness and had no idea what a clinical psychologist or psychiatrist was. There was nothing like a counsellor at school (I think i might be wrong here: there might have been a nurse in case we broke our leg in break – might).
I’m not so bad now, but I am still pretty obsessive, and occasionally something comes along that I just can’t stop thinking about. I know everyone has their worries but talking to other people about worry, obsessional thinking is completely different. It’s all consuming. It can be dangerous. It can be a form of self-harm. Mostly now I just have a “completeness obsession” – the idea that if a read a certain book or hear a particular piece of music I will be a better person. That isn’t unnatural, but then comes the idea that just owning a certain book, or worse all books in a series, or all pieces of music, will do the job. Or having every track on a music programme. That can work out to be quite expensive, and it takes a bit of time, but it doesn’t make me very unhappy. When I was 12-13 I was very, very unhappy about it all.

My experience is that obsessional thought goes with compulsive behaviour, and therefore it does make sense to talk about OCD, and the relative amount of obsession and compulsion is on a continuum. When I was young I was more compulsive; now I am more obsessional.
I wish I could be optimistic about treatment. There are no specific drugs; SSRIs and anxiolytics are usually prescribed, but they don’t seem to do much for me, and neither has CBT (although of course you might argue I’d be even worse without these).
You might also be interested in Rose Cartwright’s book Pure. Personally it didn’t tell me much new, but you might have a different view.
If anyone has come across a reliable way to stop obsessing about something, please let me know. It might be extreme, but sometimes I wonder if giving myself an electric shock every time I had a bad thought would work.