Hi, you seem to be having panic attacks. And checking the door or light switch or gas is not paranoia, it is a type of anxiety called obsession-compulsion. I know that this is all very Distressing, but it can be managed.
Next Steps
You need get a detailed evaluation with a psychiatrist and he may initially recommend relaxation exercises and therapy. If he feels that the anxiety is too severe, he may recommend medication to reduce the anxiety initially and then switch over to therapy.
Health Tips
*there is always a solution, you just need to find someone to walk you to it*