The police just want your case to go away. They don’t want any more paperwork, court appearances or distractions if they can brush you off. They’re too busy out there writing parking tickets. My suggestion: write a letter to the police detective’s supervisor with a copy to the Mayor’s Office. I think the police can reconsider whether to pursue a case and may do so if you apply some pressure on them.
Also, can you post the name and plate number of the vehicle? Maybe someone will know the driver so you can go after her in civil court. It would be easier to prove your case, however, if the police had
prosecuted her and actually convicted her of something. Without this conviction, she can also “not remember” in civil court. Then it’s your word against her, although you have a corroborating witness. Also, the burden in civil court is less than criminal court, so you would probably prevail.