That's really strange, because the EXACT same thing happened to me last year! I got asked back to my top 7 for second rounds and only got asked back to my seventh choice for pref. Like you, I dropped out, but my rho chis never gave me withdrawl forms with my info to be sent out for cob. They explained to me because there was an unusually large number of girls rushing, that it's very common to slip through the cracks even if the girls that talked to you loved you...and I realize just how true this is, having gone through rush on the other side this year. Other than that, it could be any number of things that only the individual chapters would know.
What I did, and what you might want to do, is contact your school's panhellenic office to find out when spring rush is and who is doing it. If any of the sororities sound appealing to you, then try it! That's what I did...Chi Omega lost a lot of seniors to graduating and so we did spring rush...and by coincidence, they were my top choice in the fall and now I'm an initiated sister!!!
And even if your top choice isn't doing spring rush, you might want to give it a try anyway...you might end up liking a different house than you did this fall. But if you do not want to do spring rush, if it's really important to you that you get into one of your top choices from the fall, I'd wait until next year. Besides, you'll be able to get to know a lot more girls in the house...which will give you a good advantage!!!
Good luck with what you decide!!!
