That's how my checking OCD started. It started when I was in high school. I started flat ironing my hair, and before I would leave for school, I would double and triple check that I turned it off (so I wouldn't burn my house down).

Then when I moved out and got a place of my own, I started worrying about locking everything before I left for the day. Then I started worrying about whether I turned off the stove, it didn't matter if I hadn't even used it that day. I would still check it.

Now fast forward to five years later, I have a whole ritual I have to do before I feel safe enough to leave. It is time consuming and it has even made me late for work.

As I added more responsibility to my plate, it seems that my OCD became more intense. I do think you have OCD. I didn't know I had it until way later in my life and I wish that the previous therapists I saw to help me with these feelings treated me for OCD. Instead they treated me for Borderline Personality Disorder, which they confused for my PTSD.

There is tons of literature online and at the bookstore on OCD. There's even Youtube. If you haven't already, see a therapist, preferably one who specializes in anxiety and the umbrella of disorders. If you go to someone who is unqualified like I did, I went to three who did not know what they were doing, they will unknowingly feed your OCD and will not improve it.

Best of luck to you!