I haven't been officially diagnosed with OCD, or even meet the official criteria, but can certainly identify with the obsessive thinking and inability to push thoughts out (I am diagnosed with anxiety and medicated for that, however). In the past I've been consumed with the idea that I had done something terrible on the drive* home from work (with no evidence) even driven back to the location to look, and there was nothing (but "what if it's just been cleared already"..)
My answer to the compulsively checking is: to have a "checklist" for everything, mine is a silly song (but it doesn't have to be exactly that, of course) when you go to bed or leave the house etc to go through the "checklist" - taps (faucets if you're in the States!) off, extension leads switches off, oven off, windows closed, front door locked, etc etc. What are you concretely worried over, list out those things (Ti) and make it the basis of a more benign routine. You have to acknowledge that these things worry you and not just "block them out"
In my case I have particular anxiety with overtaking a cyclist while driving. So I have a silly-song-checklist for that, "looked ahead, gone past them, looked in mirror, seen they are still cycling!! Yay
" etc.
Agree with yourself to give in to "checking"
exactly once and trust yourself to have done it once you have given in and checked. ("Giving in" isn't failure or anything - just recognition of an outside force..!)
Trust in your ability to detect quickly (Ne) if anything is "odd".
Ultimately mine didn't get significantly better until being on anxiety meds, but that was because they finally gave me the space to sit back and analyse. If I had had that perspective initially (which it sounds like you do) I could have done that to begin with!
* The irony with the anxiety meds is they have a caution, "driving reactions may be impaired"; my feeling is I'm a far better driver once on meds, than before!
