If I was charged with disorderly conduct but the citation reads "possessed marijuana", am I being charged with a disorderly conduct or possession?

A citation is what the police officer decides you are guilty of.  The prosecuting attorney decides what charges to file.  Specifically, the police provide the evidence to the prosecuting attorney who screens it.  After it has been screened for charges the prosecuting attorney will decide what charges to file with the court.

In your case, it appears that the officer charged you with disorderly conduct and noted that you possessed marijuana.  That said, the prosecuting attorney could decide to charge you with possession and not the disorderly conduct or both.

Hope this helps