Do I feel like I missed out? Yes. But I was talking to another alumna initiate (well, soon-to-be intiate) at an A Phi event this afternoon, and we said that based on our personalities, we feel that we're better matched with the kinds of events that happen on the alum end of things than the kinds of things that happen as a collegiate member.
My experience as an alumna initiate won't compare to the experiences that collegiates share, but in my eyes they shouldn't compare, because they're completely separate. My alumna experience has been very rich, and I've been made a better person by it. It's not better, nor is it worse - it's just different, and I'm okay with that.