sdt, cob and so on

Dropped before pref?
There IS a way.
Sigma Delta Tau is an NPC sorority that is housed on the other side of campus. They will host recruitment meetings next week, I believe.
And, believe it or not, in about two or three weeks, some of the sororities will pick up a few more new members through Continuous Open Bidding.
Things happen - girls withdraw, drop out, resign, just don't show up.
In about a week, sign up at the Panhellenic office for COB. You may get a call from a sorority member inviting you to lunch at the house, or coffee, or a movie night at an apartment. After you meet several sorority members, you may get an invitation to join.

Same thing will happen in the spring.
Sorority members graduate, don't return for second semester etc. and some of the sororities will have openings they'd like to fill.

This will be just a FEW of the sororities...not necessarily what everbody calls "lower tier" but occasionally event the biggest ones fill spaces.

Meet and be a friend to everyone...get involved on campus in something of interest. Get really good grades.

It can still happen.