lol
understand this, if someone rear ends you, you basically have their balls in your hand. you call the shots. what you should have done was go and get an estimate and serve him up the bill. Unfortunately you went to the reporting center and filed. Which means you are more or less turning things over to your insurance company, which in turn will contact his insurance company. and at the end of the day will sooner or later fix your car.
Your conversation with the other guy will not be so friendly once he finds out you broke the agreement and filed a report. He doesnt have to pay you anything now because its out of your hands, your insurance company will take care of it. His insurance can and almost certainly will go up, yours will remain the same because you are not at fault.
Unfortunately, had you gone directly to him you could have named your price. and he is willing to pay a premium to pay your damages and keep it off the record. you could have repaired your bumper and afford enough to buy a lip or something