Will I automatically face the max penalty from that crime of 364 days in jail plus whatever the crime is for reckless driving if convicted?

I got in a car accident where the other person has no insurance and I have bare minimum insurance on a loaned car. The officer on scene gave me an exchange of contact information as my only paperwork along with his business card stating that he would look over whether it was a reckless driving infraction or not and email me the next day with what he decided to put on the form. Is this legal for an officer to do or must they charge you on the scene? He didn't even offer me a case number. The same day, I just left court for a malicious mischief charge of 3rd degree which I pleaded guilty to in exchange for a 12 month deferred sentence on the grounds that no further criminal action was done in that 12 month window.