Hi, I had gone through your question and understand your concerns. The erectile dysfunction is not caused by intercourse during menses. In your case it likely to be due to performance anxiety or being worried about not having erection itself. (How I am acting or performing during sexual activity). Do not focus on your performance during sexual act. Just enjoy the act itself by focusing on pleasurable sensations with your partner. If your problem of insufficient erection persists, then, you may need expert s guidance by psychiatrist well versed with psycho sexual therapies. Hope I have answered your question. If you have any further questions I will be happy to help. Wish you good health.