All incidents should be reported to your insurance company even if the police are not called. This way, they have a record of your side of the incident. This also protects you from incidents such as the one you mention wherein the information later changes.

You should contact your insurance company, if you haven't already, and explain to them what happened. At this point, it will be up to a claims adjuster to determine whether or not a claim can be made against your policy. The same would be so for the other party.

You can find out how accidents and claims affect your rate by getting a direct insurance quote here.