It's been a while since I read Meditations, but that wasn't my reading at all:
While recognizing some fundamental realities, most meaning is ascribed by people, often in a way that doesn't serve their own long term happiness or well being. The task then becomes to discard with useless, contrived meaning and replace with with a sense of meaning(s) that does serve to facilitate a life worth living. This often requires foregoing pleasure and ignoring the petty opinions of others. In a sense, because 'nothing matters,' everything matters.
It also worth nothing that Meditations wasn't a book meant of to published, but a diary.