I am so extremely sorry for what you went through when you were a teenage girl.

As a survivor of abuse in therapy myself, it pains me to read stories like yours, and it pains me especially because I know that more often than not justice doesn't get served in those cases.

Unfortunately, if you don't have any evidence of what went on during your sessions with him, your report will not produce a desirable outcome (which is to hold the abuser accountable). You can still report, but without an evidence nothing will be done to him. The only reason it might be worth reporting is if you feel the fact of reporting, in and of itself, will help you to deal with your pain somehow. Otherwise, if you are hoping for justice to be served, it's not worth it.

Just out of curiosity, did you ever tell your parents about what he was doing with you? Not that it matters. It's just if you started therapy at 14, then it must have been by your parents initiative. And, usually, parents communicate with the therapist about their child's progress. So, I am just curios if your parents were involved in your process at all.

I don't know if you have reached out for support here or in other places, but, at this point, getting whatever help you need healing your trauma may be the best you can do for yourself.