Keep working on bringing up your GPA, and you will be much more desireable as a potential new member!

Involvement in various school activities (clubs for example) is also a big plus. MTSU sororities tend to be very open to having older girls join if they meet all the other requirements anyhow. New sisters who are not freshmen are less likely to drop out (or be kicked out-which would only happen as a result of SERIOUS deviation), because they are usually more stable in the following ways:
<b>academically: more likely to be focused, have good study habits, etc.
<b>financially: more likely to have a good, steady source of income, as well as possibly have money saved up for the occasion of sprority dues
<b>emotionally: less likely to be overwhelmed by the whole college experience, less likely to suddenly go "wild" because of college freedoms, more enthusiastic about being involved in the sorority and/or wanting to take on leadership roles within it, etc.
So honestly, at least as far as MTSU is concerned, age is not a HUGE deal, although I can't speak for all the sororities. Although many do PREFER freshmen, that certainly does NOT mean that they WON'T accept older girls.
Hope I've helped you out, and good luck in school and with your future endeavors!