Melissa, there's nothing wrong with you. It takes a lot of courage to go through formal rush, particularly if it's your second or third time. Great people get cut all the time, sometimes for stupid reasons... sometimes good people are cut by all sororities before they even get to pref. So you were cut heavily... it's the sororities' loss.
You might find your home via COB, or alumna initiation might be the thing for you. The important thing is not to beat yourself up over this. Spend some time with your friends, eat a pint of Ben and Jerry's, take a long bath, whatever... then move on and leave this behind you.
Take care.