No, you are mixing up several things:
-You don't need to be arrested to be tried for a crime. Be happy that you were not arrested. An arrest shall only make sure that the accused will stand trial. If the system trusts you to come to court on your own, it will not arrest you. If you fail to go to court, the judge can and probably will issue a bench warrant for your arrest. Then you will go to jail.
-The Miranda warning has nothing to do with either an arrest or a trial. It only says that before a law enforcement officer interviews you to the crime you are accused of, they shall read you these rights. If they don't they are not able to use what you said in the interview in court. They still can arrest you and try you in court, though. In your case it is pretty irrelevant what you say in an interview. The main evidence against you is the cannabis.