... it's a struggle to keep any level of focus on alumnae relations and outreach. If I had a dollar for every time I heard a young alumna (and not only of our sorority, BTW) complain that once she graduated, she never heard about anything, I'd have enough to endow a Foundation scholarship!
Collegians are focused on their own very busy lives, including their studies, their jobs, their loves, and the details of their chapter events. When they do remember to tell alums about upcoming events, it's often about 3 days before the event itself (which works less and less, schedule-wise, the older you get). This is one of the things I have simply learned to accept over time as the reality of being an alumna. It will not change.
If you want to be involved (and it's clear that you still feel lots of love for the chapter), then I encourage you to either (A) be sure that the Chapter Advisor and/or AF knows that you are willing and available to be an advisor or (B) join forces with the other alumnae around you, and come up with events and activities that, by definition, will involve the chapter. You sort of have to insert yourself into their calendar and lives -- serve things up ready-made, such as "dinner with the alums on X Date" -- or call the CP or other officer to request the chapter calendar, explaining that you want to be sure the alums are prepared to support the chapter the way the members need and deserve to be supported. (But then be sure you're involving yourselves to a level appropriate to alumnae -- that can obviously turn into a whole different issue.) As with almost anything in a volunteer organization, you really need to take the bull by the horns and steel yourself with the mantra that Alpha Xi Delta is your sorority and, come Hell or High Water, you're going to continue to work to make it the best it can be. Successful chapters are not made and maintained by passive collegians or alums, so don't feel obligated to sit on any sidelines!