Bumped Car

I bumped into a parked car on Saturday morning. I pulled around to a side street and the walked back round. There were two cars parked together and I couldn't see any marks but it was dark. I only had a small slip of paper so I put my name and number on one of the windscreens. I checked my car and there was a scuff. Nothing serious but of course if this was the other way around, I'd want to know. I didn't have my phone on me to take a pic and it was too early to start banging doors. I returned later on in the day and both cars were gone. I have been back now of 4 occasions but nothing and I haven't heard anything. Stupidly, I haven't reported this to the police within the 24 hours and am now panicking that this will become something serious. I would report but am worried that I will be charged for leaving it so long (which was of course my error). I am returning to the area shortly to knock doors as I would rather nip this in the bud without the police of course. The area has a factored/managed building so I was also thinking about contacting them to see if they had heard anything but didn't know if that'd get me anywhere. I have never had any offences before and am wracked with guilt. I could have/should have taken other actions at the time but, I was panicked/stupid and extremely worried.

I also know how annoyed the other owner would be if there was in fact noticeable marks (which of course could cost a lot more than face value would suggest). Should I report now, although late and/or continue to try and get in touch with the other owner. Any thoughts/help would be appreciated.