If one of the big problems is people not coming to things does this mean you don't have a fine system set up? I know that at the Chapter here in my city the girls are given two "passes" to chose/use to not come to something (not the two big fundraisers), but after that they get fined. They even have dates set up before an absence that you have to submit your not attending or they would still get fined. Of course there are always exceptions, but they are submitted and reviewed so girls can't just say, "I don't wanna." Well they can but they are charged for it.
This school is very tough, the chapter cumulative is very impressive, and they still make it in droves to events and chapter. If this is indeed something others see besides you then it might be time to set in place more structure.
Also like everyone else has said, if you are NPC then there are definitely resources for you and your chapter to use.
"To the world,
I promise temperance and insight and courage,
To crusade for justice,
To seek the truth and defend it always;"
- Dorothy Mumford Williams, The Delta Zeta Creed