Id like to say that you must really use your head when it comes to joining a sorority. Since there is so much dedication and effort put into becoming a sister it can be EXTREMELY over-whelming. It's recommended for women to have a strong GPA because it sort of proves that you are capable to balance the heavy workload college can be and mix the the workload of being in a sorority.
If you are in so many activities now and your GPA may not be wher you'd like, try focusing on fewer activities and more on your grades. If you graduate with at least a 3.5 and your are able to successfully complete all your other programs you shouldn't have TOO much diffculty balancing recruitment.
Also, some schools require that PNM be a full time student for at least one semester before RUSH. This is to help you adjust to college life and have opportunity to gain an understanding of how you might handle a full course load and being a part of Greek life.
Didn't mean to be so lengthy...
Hope this helps~