I have just joined this forum today after many years of OCD symptoms. The focus of my OCD has varied over the years, and currently mainly centres around contamination, but many of your compulsions of checking doors etc, even videoing to “prove” things have been done are things that I have done in the past. Also like you, it started off as something almost funny or “quirky”- I remember having a laugh with a friend who came to stay at my flat about the fact I had a little notebook that I ticked off all of the things I had to check before I went out, then I posted it through the letter box once I had ticked off “locked door”. But as OCD does, it has spiralled since then (and changed its focus somewhat.)
As I said before, I have also just decided today that something needs to change in my situation, so I don’t really have any wise words for you- just that you’re not alone and there are people here who understand you. We can get through this.