Why fill out a police report?
A report is only helpful to collect money for your damages, (especially if you think the other driver will not pay her fair share) or if you feel that the other driver was doing something illegal, such as driving drunk.
Otherwise, the report can only do you harm, such as going on record that you had an accident, which may increase your insurance rates, even if the accident was not your fault.
The police may not be willing to file a report if it was on private property, with minimal damage, several days after the incident.