grades

How is it possible to get a 2.8 in high school?

You will be cut from Ddd, xo, kd, dg, phi mu, and kappa. Guaranteed.

Unless you are a legacy or have major connections.

adpi and theta are the only ones that you will probably have a chance with. or alpha phi. but don't let that discourage you, i promise that once you are in a bottom tier house you'll love it just as much as the girls in the top tier houses love theirs.

There's going to be AT LEAST 1,800 girls going through rush this year. There's a rumor that 1,900 girls have registered and the deadline is still a month or so away. Now with 1,800-1,900 girls going through rush and (now) 11 houses with open spots, you will be limited.
I'm sorry. XO, DG, and KD will cut you unless you're a chapter legacy or you have a lot of connections after the first day. Kappa, Phi Mu, AOPi, and Pi Phi have raised their academic standards so you'll need to really shine or have some friends in those sororities. However! You still have Theta, ADPi, and Alpha Phi to choose from!
Theta is full of great girls and ADPi is getting their new house this year! And it might be really fun and awesome to be a founding sis for Alpha Phi! Just think of the opportunities!
You will find your home, but your choices are very very limited.

No one wants a grade risk. Theta, ADPi, and Alpha Phi are your best bet.
Just like the girl above me said, this year is going to be extremely competitive and sororities have raised their standards. Their minimum might say 2.8, but they really don't want a grade risk unless you have an excuse why you have a low GPA.
You better have a good resume, have your recs and letters sent, and an outstanding personality too. Cause I don't think Theta wants any more grade risks either

I will tell you with great confidence that you will not get a bid to Theta. Not a chance. Not sure if you could get past the first round, but you won't get to Pref with Theta.