Airdog - sounds like you got caught out a bit, which is not unknown for pretty well any pilot. Good to hear that you're OK - as others have said already, a 172 can be a bit of a sod if you're carrying too much speed (=energy) into the flare. The sprung undercarriage will also reward an excessive sink rate onto the runway with a nice bouncy landing!
Just a word of caution - not trying to teach you to suck eggs here, but may be worth getting an engineer to do heavy landing checks on the aircraft, just in case there is some latent damage on the aircraft. Just would wish to avoid the person after you (or someone in a few weeks time) having a nosegear collapse as a result of undiscovered problems from today. I was a group owner in a PA28 that had a buckled firewall discovered on a C of A check, with no reported heavy landings in the log. That had 2 concerns - one was, there couldn't be an insurance claim to cover the repairs as no-one owned up to it, secondly, there had been a real risk of a nosegear collapse in the intervening period.
Good luck - it'll come in the end (I've been saying that for the last 175 hrs - I still manage to pull off some shocking landingson occasions!!
).