This is actually completely possible and does happen. Feeling that one can not perform sexually with one gender can force them away from that gender psychologically, and they begin to question and theorize their options and themselves.

Also, to the OP, a female friend of mine's husband has a small penis. They have amazing sex anyway according to her. They have long foreplay devoted to pleasing her orally and through toys, massage, and sometimes they do things like roleplay, etc. He also eventually started using some sort of strap-on as well. He still delivers the full package.. And I suppose more to compensate. I absolutely suggest toys and learning how to have and give amazing foreplay. It will help with your self-esteem. therapy is great but you know the root of your problem. But there are other ways to perform. Some women out there really like penetration but others find it uncomfortable and even painful. I myself prefer outer stimulation and actual sex is often painful for me.