Google under "self mutilation disorder" or "self harm disorder". I have read that often it stems from prior abuse of some sort. Low self esteem is probably involved also. Talk to your school guidance counselor and check in the library for books on this subject.
The bigger question is why were you driving without plates and insurance?
You could pay money to get a car history at carfax.com. See if it was in any wrecks in the past. You definitely had a bad day, but at least you hopefully were not injured and thankfully (without insurance) neither was...