Glad to hear you're (mostly) OK. Follow the sound advice copcake_ham gave you. As a former police officer (crash investigator) and a private investigator, I'd add that from this point forward, DO NOT talk any further about the accident to anyone, remember, everything we type on the internet can be found anytime by anyone who wants to find it. Be sure not to say anything later either in person to someone, or here, like: "Well, maybe I should have looked behind me." (I know you shouldn't have, I'm just giving an example) A simple thing like that can be the difference between success and failure in your suit.
Bobofish, I was also in a similar crash when I was 15 and know how scary it must have been for you. I'd remind everyone that if a hit-run happens to you and the other driver gets away, that there's a very good chance that he is on a regular route. The police, you, or someone you hire, should sit by the side of that road for a while, and yes, a lot of times the car drives right by the same time the next day, next week, etc. Also- that old guy probably wasn't more than a half mile from his house, someone could have tried to find him if deemed necessary.
Best of luck in your recovery, let us know how you make out from here on, but DON'T say "I'm fine"! 😀 (for obvious reasons)!
