Ok, I'm obviously not in a sorority because I'm a guy, but some of my female best friends are. The only time conflicts that my friends have had was during pledging week where they had to do whatever their sisters asked. Otherwise, most of the sorority type stuff happens during the weekend nights (aka parties/drinking :beercuphe). The sorority does do some volunteer type stuff on occasion and the sisters have formed very close bonds with eachother.
Honestly, I have not seen any conflicts with the workload of being a nursing student. However, I do see some conflicts in your situation considering that you have a young child who needs your love and attention. I don't know if you want to join a sorority for the drinking and parties, the close bonds, or whatever it may be, just keep your priorities in order (your child and education before the sorority). The duty of being a mom surpasses any of this and you want to make sure your child wont be impacted by any negative decisions.