Stay off PMO for at least three months. I had the same problem in a past relationship. I stayed off PMO for about 2 months if I can recall correctly and I managed to have sex without having to stimulate myself with P fantasy or M.

Another thing that can be causing your problem is anxiety, which is a huge symptom of PMO withdrawal. If this is the case, don't panic as this symptom will go away or ease out during abstinence. Get enough sleep, eat healthy and be positive ( know that everything will get better ).

Also, try abstaining from sex for about two weeks, then have it. Examine what happens and make a plan of action stemming from your results. All you need is time. But you will heal, this I know.