Hello, I've had OCD since I was a child, which peaked at a severe form when I was around 22 (I'm 27 today). My OCD is close to the form of pure O, and I learnt to live with my brain: a) creating unpleasant scenarios multiple times a day; b) generating specific anxiety thoughts on everyday things.
I was on a high sertraline dosage years ago, it kind of helped. Now my OCD it's milder so I'm on a ligther dosage.
With time, I came up with a few suggestions I wish the younger me knew.
The first you have to remember is that higher dosages WILL NOT stop obsessions. They will show up, less often, but you can still have a peak of OCD thoughts during therapy.
Do not associate stimming/fidgeting/squirming to OCD thoughts, or it will become more and more automatic and harder to stop. The less consciously this happens, the harder will be to stop it. I used to swing a lot anytime my brain was producing scenarios... it took me more than a year to stop that.
A useful idea is not indulging in thoughts, as soon as they show up. It will be weird to realize how blank your mind can feel when freed from thoughts. This is not permanent though, it can be trained, but if you are OCD, well, you will always be. So, if you manage to get your mind blank, try to focus on something you really enjoy that helps you lower your anxiety. In my case, singing helped, because it entailed both my body and mind. It fully absorbed me and left no room for OCD.
Do not talk to non-therapists about your thoughts, unless they have time to listen and you're calm enough to organize them into words. It's a double edged sword, because it might even strenghten the activation patterns that lead to obsessions.
When I was in my severe phase, a doctor told me I could even develop a psychosis. I did not, luckly. But I had to quit university for six months. Had hard time sleeping. I literally needed months to relax and cool down.
I write this in the hope that someone find it helpful.