From what I heard, first offense - misdeameanor that does not have a maximum punishment of more than a year in jail would be considered not inadmissible for immigration purpose. So you should be ok. If it is a felony - then it is a different story.
For immigration purpose, BCIS sees the maximum possible punishment for a crime, does not matter what actually was served. Is your crime felony/misdeameanor? and what could have been the maximum punishment? irrespective of what you are getting from the DA?