A misdemeanor will not disqualify you.
However, your criminal record prior to your 18th birthday should be erased on that birthday.
Your best bet is to never mention those charges ever again. It is very likely no one will ever come across them again. As soon as you finish reading my answer, you should become "Mr. Never Been Arrested". I do, really do, hope you didn't put those offenses down if you've already enlisted because THAT is often the only way organizations ever find out about a person's juvenile record. They play on the young person's naive mind, who does not realize the juvenile record was destroyed when they were no longer juveniles.
I was an Army officer myself. If being an officer is more important than MP, you should consider one of the combat arms MOS's. It will be easier down the road. An Army division typically has only one MP company, while it has dozens of officer openings in Infantry, Artillery, and Armor.
I was also a cop in the Dallas Police Department. An ex Army Officer, non MP, will get hired before an enlisted MP below the rank of E7.
If you haven't written down those charges on any paperwork yet, then your record is as clean as mine.
If you screwed up and already done so, then you should be fine as long as you've never been in trouble after that 18th birthday.
You might have a better chance of getting OCS when your first four years are ending. You can use that as a bargaining tool at reenlistment time. You will only be 26, the same age as me when I applied to OCS, plus the Army will have already gotten its enlisted use out of you. You should be an NCO by that time, which will also help you get in.
If you haven't enlisted yet, you better get Jump School tossed in.