Why don't you try calling your headquarters? I am sure that someone there can help you.
You can also try Newcomers' Club -
www.newcomersclub.com/md.html
It is primarily a women's organization but men are welcome to join too. Its purpose is to help new residents get acclimated to their town and offers a wide variety of programs. Just like in your sorority each chapter/club is different. I am the youngest in mine and I will be 35.
The age difference isn't really that big of a deal. We all like to have a good time.
Good luck to you and your fiance.