Thank you for your question. I look forward to working with you to provide you the information you are seeking for educational purposes only.
In a sexual harassment case as you describe, you need more evidence than your word against his. That evidence can be an audio recording of him harassing you or some co-worker who has experienced the same sexual harassment from him. The EEOC requires some type of evidence to support your claim, which is why you were told yesterday your case was weak.
So you have to either record him harassing you or find some witness with the courage to come forward to testify against him.