Your sorority is gorgeous! I agree with adding some floating plants, otherwise it looks perfect.
I have 9 girls and 1 baby (in a breeder box)and 3 otos in my 29g, and Aqadvisor says I can still add more fish...I want to add cories and some kuhli loaches, and who knows...maybe another female or two. If you have the right filter and time to do extra water changes, why not add more?!
I actually have a 55g tank in my garage right now...it used to house garter snakes and I have no idea if it'd hold water. I'd love to see it hold fish...someday. :)