I need an awesome backpack

I'm premed and a girl, so naturally  carry everything with me at once. I am currently switching to eBooks so I don't have to lug around textbooks, but I do carry a MBA, iPad 2, and giant spiral notebooks with supplies, my medication, bike stuff, water bottle, lunch box, random school supplies, notecards, gloves, stethoscope, etc... at all times.

Right now, I have a dinky little dakine backpack that is ripping because there's not enough room to put in all of my things. I've been looking into the Motherlode TLS Weekend Convertible eBags but was wondering if there was anything bigger. I need it to stick out more like a giant turtle shell on my back. I need it to go out that way, not side ways. Lots of room! Any suggestions?

Thanks!